Suppression of inflammation and acquired immunity by IL-37

IL-37 improves palmitic acid-induced lipid deposition in liver cells by inhibiting ferroptosis to regulate macrophage polarization

Non-alcoholic fatty liver disease (NAFLD), which acts as a predominant contributor to chronic liver disease, remains a pervasive global epidemic. Interleukin-37（IL-37） is documented to have protective effects against various liver diseases. This work focuses on investigating the role and relevant action mechanism of IL-37 in NAFLD. Immunofluorescence assay and Western blot（WB）were used to estimate M1 macrophage markers. For immunofluorescence analysis, images from five randomly selected fields per sample were captured using a confocal microscope (Leica). Fluorescence intensity was quantified by ImageJ software (version 1.53) with background subtraction, and data were normalized to DAPI-positive cells.The lipid Reactive Oxygen Species（ROS）and cell lipid droplet deposition were assessed via BODIPY 581/591 C11 staining and Oil Red O staining. Fe2 +, triglycerides and cholesterol levels were assessed utilizing appropriate assay kits. WB was adopted for the estimation of proteins associated with ferroptosis and apoptosis. Protein band intensities were quantified using Image Lab software (Bio-Rad) and normalized to β-actin expression. Three technical replicates were analyzed for each biological replicate (n = 3). Our data revealed that IL-37 alleviated PA-stimulated（Palmitic acid-stimulaed）M1 macrophage polarization. It was also identified that IL-37 suppressed lipid accumulation and apoptosis in RAW264.7 cells through inhibiting the polarization of M1 macrophages. Collectively, IL-37 could improve PA-stimulated lipid accumulation and apoptosis in liver cells through suppressing M1 macrophage polarization, which might be mediated by ferroptosis.

Human regulatory B cells suppress autoimmune disease primarily via interleukin-37

Regulatory B cells (Bregs) are crucial for maintaining homeostasis and controlling inflammation. Although interleukin (IL)-10 has been traditionally suggested as the primary suppressive mechanism of Bregs in both mice and humans, the key functional differences between Bregs in these two species, particularly in the context of disease, is still largely unresolved. IL-37, the latest described immunosuppressive cytokine, is produced in humans but not in mice. Herein we identified the characteristics and functions of IL-37-producing Bregs, that naturally exist in human and can be induced by recombinant IL-37 (rIL-37) and/or Toll-like receptor 9 agonist CpG via different mechanisms. rIL-37 alone is sufficient to prompt IL-37, but not IL-10, production and proliferation of Bregs, whereas CpG elicits IL-37 expression in Bregs independently of IL-10, but dependent on HIF-1α which binds on the enhancer/promoter of the IL-37 gene. Functionally, IL-37+ Bregs exhibit superior anti-inflammatory efficacy than IL-37- Bregs in vitro, as well as in psoriasis and colitis models. However, the frequency of IL-37+ Bregs is reduced in patients with psoriasis. Thus, IL-37+ Bregs hold significant therapeutic potential for treating various inflammatory disorders, including psoriasis and colitis.

IL-37 Protects Against Ventilator-Induced Lung Injury by Inhibiting NLRP3 Activation

Mechanical ventilation is an effective strategy for managing acute respiratory distress syndrome (ARDS), but it can also exacerbate lung injury, leading to ventilator-induced lung injury (VILI). To investigate the protective role of interleukin-37 (IL-37) in the pathogenesis of VILI, we used two approaches, human IL-37 transgenic (IL37tg) mice and administration of recombinant human IL-37 (rIL37) in wild-type (WT) mice subjected to mechanical ventilation. Lung histopathology was evaluated, inflammatory cytokine levels (IL-1β, IL-6, TNF-α) were measured, and inflammasome activation was assessed by analyzing NLRP3 and Caspase-1 expression. As a result, IL37tg mice exhibited significantly attenuated lung injury compared to WT controls, characterized by improved histological morphology, reduced lung injury scores, and decreased infiltration of macrophages and neutrophils. Similarly, rIL37 administration markedly reduced lung injury and decreased inflammatory cytokine levels. Immunofluorescence analysis revealed colocalization of the alveolar cell marker surfactant protein D (SP-D) and IL-37. Furthermore, IL-37 suppressed NLRP3 inflammasome activation, as evidenced by reduced NLRP3 and Cleaved-Caspase-1 levels in both the IL37tg mouse model and the rIL37 treatment group. These findings suggest that IL-37 effectively protects against VILI by inhibiting inflammation in lung tissues through inhibition of the NLRP3 inflammasome. Therefore, IL-37 may serve as a potential therapeutic target for the prevention and treatment of VILI in the future.

Computational modeling of the anti-inflammatory complexes of IL37

Interleukin (IL) 37 is an anti-inflammatory cytokine belonging to the IL1 protein family. Owing to its pivotal role in modulating immune responses, elucidating the IL37 complex structures holds substantial therapeutic promise for various autoimmune disorders and cancers. However, none of the structures of IL37 complexes have been experimentally characterized. This computational study aims to address this gap through molecular modeling and classical molecular dynamics simulations. We modeled all protein-protein complexes of IL37 using a range of methods from homology modeling to AlphaFold2 multimer predictions. Models that successfully recapitulated experimental features underwent further analysis through molecular dynamics simulations. As positive controls, binary and ternary complexes of IL18 from PDB were included for comparison. Several key findings emerged from the comparative analysis of IL37 and IL18 complexes. IL37 complexes exhibited higher mobility than the IL18 complexes. Simulations of the IL37-IL18Rα complex revealed altered receptor conformations capable of accommodating a dimeric IL37, with the N-terminal loop of IL37 contributing significantly to complex mobility. Additionally, the glycosyl chain on N297 of IL18Rα, which contours one edge of the cytokine binding surface, acted as a steric block against the N-terminal loop of IL37. Further, investigations into interactions between IL37 and IL18BP suggested that a binding mode homologous to IL18 was unstable for IL37, indicating an alternative binding mechanism. Altogether, this study accesses to the structure and dynamics of IL37 complexes, revealing the structural underpinnings of the IL37's modulatory effect on the IL18 signaling pathway.

Interleukin-37 reduces lipopolysaccharide induced matrix metalloproteinase-9 in gingival epithelial cells

BACKGROUND

In periodontal diseases, the recognition of pathogen-associated molecular patterns (PAMPs) triggers signaling cascades that lead to the release of matrix metalloproteinases (MMPs). Interleukin-37 (IL-37) is recognized as a key suppressor of the immune response. This study aimed to detect the expression and distribution of IL-37 in gingival tissues and analyze its suppressor role in MMP-9 in response to lipopolysaccharide (LPS)-stimulated gingival epithelial cells.

METHODS

Immunohistochemistry localized IL-37 in gingival tissues from periodontitis patients and healthy controls (N = 10). The induction of IL-37 expression by LPS was analyzed using the conditioned medium of gingival epithelial cells through enzyme-linked immunosorbent assay (ELISA). To determine the relevant MMP-9 levels in epithelial cells following exposure to LPS alone or in combination with IL-37, both quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA) were performed.

RESULTS

Cultured epithelial cells secreted significantly higher levels of IL-37 when stimulated with LPS compared to unstimulated controls. Both ELISA and qPCR showed that LPS stimulation significantly increased MMP-9 levels. However, co-culture with IL-37 markedly reduced LPS-induced MMP-9 expression at both the protein and mRNA levels. Furthermore, immunohistochemistry revealed increased IL-37 expression in periodontitis tissues, both in epithelial cells and connective tissue.

CONCLUSIONS

Gingival epithelial cells may contribute to tissue responses in periodontitis through the secretion of MMP-9 in response to PAMPs. Furthermore, IL-37 appears to have a potential role in modulating and reducing this response, as observed in the decreased MMP-9 expression following IL-37 co-stimulation.

IL-37 Alleviates Sepsis-Induced Lung Injury by Inhibiting Inflammatory Response Through the TGF-β/Smad3 Pathway

Introduction: Sepsis is caused by an uncontrolled inflammatory response and immune dysfunction, with lung injury being the most common complication and one of the leading causes of death in clinically ill patients. Interleukin 37 (IL-37) is a multifunctional cytokine that plays a vital role in various pathophysiological processes, including inflammation, infection, and immunity.Methods: The study involved both clinical and animal experiments (establishing an animal model of sepsis-induced lung injury). Firstly, 50 patients with sepsis-induced lung injury and 50 healthy controls were included. In addition, a more in-depth study was conducted using animal models.Results: IL-37, IL-6, PCT, and CRP levels were significantly higher in the sepsis-induced lung injury group. Correlation analysis revealed that IL-37 significantly correlated with IL-6, PCT, and CRP levels. In animal experiments, IL-37 significantly attenuated CLP-induced pulmonary edema and cellular injury while reducing the levels of inflammatory factors IL-6 and TNF-α, as well as sepsis-related inflammatory markers PCT and CRP. Moreover, IL-37 significantly downregulated the expression levels of genes and proteins of apoptosis-related molecules Caspase-3 and Bax and pathway molecules TGF-β and Smad3. Discussion: The TGF-β/Smad3 pathway is involved in the process of IL-37 inhibiting inflammatory response and ameliorating sepsis-induced lung injury.

Salivary Biomarkers of Inflammasome Activation in Unstable Periodontitis: A Case-Control Study

The objective of this study was to investigate the complex network of inflammasome-related biomarkers (NOD-like receptor thermal protein domain associated protein 3 [NLRP3], caspase-1, interleukin [IL]-1β, IL-18, and IL-37) in unstable periodontitis by examining the salivary concentrations of these specific biomarkers and correlating them with periodontal parameters.The design of this study was an observational case-control study. A salivary sample was collected from periodontally healthy patients (n = 40) and unstable periodontitis patients (n = 40). Full-mouth clinical periodontal parameters were recorded (plaque index, bleeding on probing, periodontal pocket depth, and clinical attachment loss). Enzyme-linked immunosorbent assay analyzed NLRP3, caspase-1, IL-1β, IL-18, and IL-37 salivary levels.The normality of the data was tested using the Shapiro-Wilk test. Mean, standard deviation, and percentages were used for data description. An independent sample t-test, Mann-Whitney U test, and chi-square test were used to compare the two groups with a p-value of < 0.05. Spearman's correlation analysis was conducted to examine the relationships between variables.In saliva samples, NLRP3, caspase-1, IL-1β, and IL-18 were the highest in the periodontitis group (p < 0.005), while IL-37 was highest in the healthy group (p < 0.005). There was significant (p < 0.012) negative weak correlation (-0.395) between IL-37 and IL-1β, and significant (p < 0.003) negative moderate correlation (-0.455) between IL-37 and IL-18 in the healthy group. A significant (0.031) positive weak correlation (0.342) was found between the salivary IL-37 and NLRP3, and a significant (p < 0.001) negative moderate correlation (-0.508) was found between salivary IL-37 and IL-1β, in the periodontitis group.The NLRP3 inflammasomes and their cytokines (caspase-1, IL-1β, and IL-18) significantly promote periodontal inflammation and tissue destruction. In contrast, IL-37 acts as an anti-inflammatory cytokine, inhibiting the activity of the NLRP3 inflammasome and reducing excessive inflammation. This interplay highlights the potential of targeting NLRP3 and enhancing IL-37 as a therapeutic approach for the treatment of periodontal disease.

From Joints to the Heart: An Integrated Perspective on Systemic Inflammation

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease which predominantly affects joints, but it can also lead to significant extra-articular complications, particularly cardiovascular disease (CVD). Chronic systemic inflammation promotes endothelial dysfunction and accelerates atherosclerosis, increasing cardiovascular risk.

METHODS

Current data were analyzed to explore the mechanisms between RA and CVD, focusing on systemic inflammation, pro-inflammatory cytokine patways (IL-1, IL-6, TNF, and JAK-STAT), and their interactions with traditional cardiovascular risk factors. Recent studies and clinical guidelines were reviewed to highlight gaps and advances in risk assessment and management.

RESULTS

Persistent disease activity and the presence of autoantibodies significantly increase cardiovascular risk in RA contributing to atherosclerosis and major cardiovascular events. Data also suggest that anti-inflammatory treatments, including methotrexate and biologic agents, may lower this risk.

CONCLUSION

This review highlights the pathophysiological mechanisms between RA and CVD, and the need for early diagnosis and active monitoring to identify and assess cardiovascular risk. A multidisciplinary approach, involving rheumatologists and cardiologists is essential for optimizing cardiovascular risk management and improving patient outcomes. Optimization of cardiovascular risk management strategies in patients with RA should be an essential component of current medical practice, with the main goal of reducing morbidity and mortality from cardiovascular complications.

Cellular and Molecular Mechanisms of Innate Memory Responses

There has been an increasing effort to understand the memory responses of a complex interplay among innate, adaptive, and structural cells in peripheral organs and bone marrow. Trained immunity is coined as the de facto memory of innate immune cells and their progenitors. These cells acquire epigenetic modifications and shift their metabolism to equip an imprinted signature to a persistent fast-responsive functional state. Recent studies highlight the contribution of noncoding RNAs and modulation of chromatin structures in establishing this epigenetic readiness for potential immune perturbations. In this review, we discuss recent studies that highlight trained immunity-mediated memory responses emerging intrinsically in innate immune cells and as a complex interplay with other cells at the organ level. Lastly, we survey epigenetic contributors to trained immunity phenotypes-specifically, a recently discovered regulatory circuit coordinating the regulation of a key driver of trained immunity.

Prognostic Value of Serum Interleukin-37 in Patients with Acute Respiratory Distress Syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is prominently characterized by uncontrolled inflammation and high mortality. The effect of interleukin-37 (IL-37) on the prognosis of ARDS remains unclear.

METHODS

This prospective cohort study detected and analyzed serum IL-37 levels on day 1 (baseline) in 128 patients with ARDS and 40 healthy controls, and on day 7 in patients with ARDS. Clinical and laboratory parameters were assayed. Survival status was tracked within 28-d of enrollment.

RESULTS

BaselineIL-37 concentration was lower in non-survivors (135.00 [87.75, 198.75] pg/mL) than in survivors (250.50 [173.25, 382.75] pg/mL) (p < .05). Non-survivors displayed a greater reduction in IL-37 levels from day 1-7 than survivors (49.87% vs. 40.09%) (p < .05). Baseline IL-37 levels were negatively associated with C-reactive protein, procalcitonin, and IL-6 levels. The area under the receiver operating characteristic curve of the baseline level and percentage decline in IL-37 was 0.755 and 0.809, respectively, for predicting 28-d mortality. Combining IL-37 with the acute physiology and chronic health evaluation II score further improved mortality prediction capability. Patients with ARDS with low IL-37 concentrations (<143.00 pg/mL) or a high percentage decline (≥44.76%) had a poorer survival rate than those with a high concentration or low percentage decline. The baseline IL-37 level and percentage decline independently predicted mortality in a univariate Cox regression model (p < .05).

CONCLUSIONS

A low IL-37 level or significantly declining rate predicts higher 28-d mortality in patients with ARDS, indicating that IL-37 may be a promising prognostic biomarker.

Interleukin-37 promotes wound healing in diabetic mice by inhibiting the MAPK/NLRP3 pathway

AIMS/INTRODUCTION

Diabetic foot ulcer (DFU) is a prevalent complication of diabetes characterized by heightened inflammation and impaired wound-healing processes. Interleukin-37 (IL-37) is a natural suppressor of innate inflammation. Here, we aim to investigate the potential of IL-37 in enhancing the healing process of diabetic wounds.

MATERIALS AND METHODS

The skin samples of DFU and non-diabetic patients during foot and ankle orthopedic surgery were collected. The IL-37 transgenic mice (IL-37Tg) were created using CRISPR/Cas-mediated genome engineering. Mice were administered streptozotocin (STZ, 150 mg/kg) to induce a diabetic model. After 4 weeks, an equidistant full-thickness excisional wound measuring 8 mm was created on the central back of each mouse and allowed to heal naturally. Body weight and blood glucose levels were measured weekly. The wound area was measured, and skin samples were collected on Day 10 for further Quantitative polymerase chain reaction (qPCR) and WB detection and RNA sequencing analysis.

RESULTS

The proinflammation cytokines such as TNF-α and IL-1β and the MAPK signaling pathway were significantly increased in the wound margin of DFU patients. Compared with diabetic mice, diabetic IL-37Tg mice showed a significantly accelerated healing process. The enriched signaling pathways in RNA sequencing included cytokine-cytokine receptor interaction, TNF signaling pathway, and NOD-like receptor signaling pathway. Through QPCR and WB detection, we found that IL-37 could inhibit the activated MAPK and NOD-like signaling pathway, reducing TNF-α, IL-1β, and NLRP3 expression in the diabetic wound.

CONCLUSIONS

IL-37 promotes skin wound healing in diabetic mice, providing a new possible target for treating diabetic wounds.

The significant role of IL-15, IL-22, IL-37, and caspase 9 in polycystic ovary syndrome: A case-control study in a sample of Iraqi women

The study aims to evaluate the significant role of interleukin 15 (IL-15), IL-22, IL-37, and Caspase 9 gene expression in polycystic ovary syndrome (PCOS), focusing on the underlying mechanisms and potential diagnostic or therapeutic implications. Peripheral blood has been collected, and serum was separated for the evaluation of the serum IL-15, IL-22, and IL-37. The ELISA technique has been carried out to determine the serum levels of understudied factors mentioned above in Iraqi women patients diagnosed with PCOS (No. = 90) via a specialized gynecologist and healthy fertile women (No. = 48) as a control group. In addition, a genetic study on the expression of the caspase 9 gene in these patients had been performed. The data reveals statistically significant differences in interleukin levels in PCOS patients versus the control group. Specifically, the PCOS group exhibits significantly higher levels of IL-15 and IL-22 as compared to the control group. Conversely, the PCOS group shows significantly lower levels of IL-37 compared to the control group. The results showed no statistically significant difference in the mean expression of the Caspase 9 gene when comparing these fold graduations. However, it's worth noting that a higher fold frequency was observed in both the PCOS and control groups, with 57.1 % and 60 %, respectively, having folds less than 1. The distribution of folds varied across other categories was also addressed. Additionally, there was a notable difference in the frequency of 11.4 % in the PCOS group compared to 2 % in the control group for folds greater than 9. The findings suggest that interleukins, particularly IL-22 and IL-37, hold promise as diagnostic markers for distinguishing PCOS from healthy conditions. However, the potential diagnostic utility of the Caspase 9 gene expression was not confirmed in this study.

The role of IL-1 family cytokines in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is the primary cause of heart failure in patients with diabetes and is characterised by contractile dysfunction and left ventricular hypertrophy. The complex pathological and physiological mechanisms underlying DCM have contributed to a limited number of available treatment options. A substantial body of evidence has established that DCM is a low-grade inflammatory cardiovascular disorder, with the interleukin-1 (IL-1) family of cytokines playing crucial roles in initiating inflammatory responses and shaping innate and adaptive immunity. In this review, we aim to provide an overview of the underlying mechanisms of the IL-1 family and their relevance in DCM of various aetiologies. Furthermore, we highlighted potential therapeutic targets within the IL-1 family for the management of DCM.

IL-37 Inhibits Inflammation of Lacrimal Gland in Dry Eye Mice via the IL-37-PTEN-NFκB Signaling Pathway

PURPOSE

This study aims to investigate the role of Interleukin-37 (IL-37) in mouse models of dry eye.

METHODS

Two murine models of dry eye were employed in this investigation.   The evaluation of the anti-inflammatory impact of IL-37 (200 μl, 10 μg/ml) on dry eye mice involved intraperitoneal injections administered once daily for 7 days. Additionally, intraperitoneal injection of VO-Ohpic trihydrate (VO, 0.25 mg/kg) in dry eye mice was performed to investigate the role of PTEN in the IL-37 anti-inflammatory signaling pathway. Tear production was assessed using phenol red cotton thread, while corneal damage was examined through sodium fluorescein staining using a slit lamp. Histological alterations in the lacrimal gland were observed through H&E staining. PAS staining was used to assess conjunctival goblet cells. The levels of NFκB-P65, p-NFκB-P65, IL-1β, IL-6, TNF-α, CD3, AQP5, α-SMA and PTEN proteins were determined via Western blotting or immunofluorescence.

RESULTS

Following IL-37 treatment, both dry eye models exhibited reduced corneal fluorescence staining scores and enhanced tear production. In lacrimal gland, the expression of p-NFκB-P65, IL-1β, IL-6, CD3 and TNF-α was diminished, while PTEN, AQP5, α-SMA expression increased after IL-37 treatment in both dry eye mice. However, the intraperitoneal injection of VO significantly attenuated the anti-inflammatory effect of IL-37 on dry eye mice.

CONCLUSION

IL-37 emerges as an anti-inflammatory mediator within the lacrimal gland of dry eye mice, exerting its effects through the IL-37-PTEN-NFκB signaling pathway.

Pulsed electromagnetic fields inhibit IL-37 to alleviate CD8+ T cell dysfunction and suppress cervical cancer progression

Pulsed electromagnetic field (PEMF) therapy is a potential non-invasive treatment to modulate immune responses and inhibit tumor growth. Cervical cancer (CC) is influenced by IL-37-mediated immune regulation, making PEMF therapy a potential strategy to impede CC progression. This study aimed to elucidate the effects of PEMF on IL-37 regulation and its molecular mechanisms in CC. CC cell-xenografted mouse models, including IL-37 transgenic (IL-37tg) mice, were used to assess tumor growth through in vivo fluorescence imaging and analyze CC cell apoptosis via flow cytometry. TCGA-CESC transcriptome and clinical data were analyzed to identify key inflammation and immune-related genes. CD8+ T cell models were stimulated with PEMF, and apoptosis, oxidative stress, and inflammatory factor expression were analyzed through RT-qPCR, Western blot, and flow cytometry. PEMF treatment significantly inhibited IL-37 expression (p < 0.05), promoted inflammatory factor release (TNF-α and IL-6), and activated oxidative stress, leading to increased CC cell apoptosis (p < 0.05). IL-37 interaction with SMAD3 impacted the p38/NF-κB signaling pathway, modulating CD8+ T cell activity and cytotoxicity. Co-culture of Hela cells with CD8+ T cells under PEMF treatment showed reduced proliferation (by 40%), migration, and invasion (p < 0.05). In vivo experiments with CC-bearing mice demonstrated that PEMF treatment downregulated IL-37 expression (p < 0.05), enhanced CD8+ T cell function, and inhibited tumor growth (p < 0.05). These molecular mechanisms were validated through RT-qPCR, Western blot, and immunohistochemistry. Thus, PEMF therapy inhibits CC progression by downregulating IL-37 and improving CD8+ T cell function via the SMAD3/p38/NF-κB signaling pathway.

SIGIRR suppresses hepatitis B virus X protein-induced chronic inflammation in hepatocytes

Although antiviral drugs can effectively inhibit hepatitis B virus (HBV) replication, the maintenance of chronic inflammation in the liver is still considered to be an important cause for the progression of HBV-related liver disease to liver fibrosis and advanced liver disease. As an endogenous inhibitory receptor of IL-1R and TLR signaling pathways, single immunoglobulin interleukin-1-related receptor (SIGIRR) has been proven to reduce inflammation in tissues to maintain system homeostasis. However, the relationship between SIGIRR expression and HBV replication and inflammatory pathway activation in hepatocytes remains unclear. In this study, hepatitis B virus X protein (HBx) upregulated MyD88 in liver cells, promoting NF-κB signaling and inflammatory factor production with LPS treatment, and the cell supernatant accelerated the activation and collagen secretion of hepatic stellate cells. However, SIGIRR overexpression suppressed HBx-mediated MyD88/NF-κB inflammatory signaling activation and inflammatory cytokine production induced by LPS in hepatocytes and HBV replication hepatocytes. Although we did not find any effect of SIGIRR on HBV replication in vitro, this study investigated the role of SIGIRR in blocking the proinflammatory function of HBx, which may provide a new idea for the treatment of chronic hepatitis B.

The effect and mechanism of IL-37d on neutrophil recruitment in the early stage of tumor metastasis in the lungs

BACKGROUND

Chronic inflammation plays a pivotal role in cancer progression, with tumor-associated neutrophils (TANs) actively shaping the pre-metastatic niche. Interleukin-37 (IL-37), a known immunosuppressive cytokine, is implicated in this regulation, although its precise function remains underexplored.Therefore, this study seeks to further elucidate the inhibitory effect of IL-37d on neutrophil recruitment within the pre-metastatic lung microenvironment and its underlying mechanisms, thereby providing a theoretical foundation for clinical interventions in the early stages of cancer progression.

METHODS

This study investigates the impact of IL-37d on tumor growth, metastasis, and survival in a murine model, with a focus on the molecular mechanisms involved. Specifically, we explored IL-37d's ability to inhibit toll-like receptor 3 (TLR3) activation in lung epithelial cells, reduce calcium-binding proteins S100A8/A9 (S100a8/9) expression, and suppress matrix metalloproteinase 9 (MMP9) activity. We also examined IL-37d's effect on neutrophil migration from the bone marrow to the lungs during early metastasis.

RESULTS

IL-37d treatment significantly reduced lung metastasis and extended survival in mice. Mechanistically, IL-37d inhibited TLR3 activation, downregulated S100a8/9 expression, and reduced MMP9 activity, thereby impairing the migration of bone marrow-derived neutrophils to the lungs. This led to decreased neutrophil infiltration and a disruption of the pre-metastatic niche formation.

CONCLUSION

Our study represents the first investigation into the role of IL-37d in inhibiting tumor metastasis during the early stages by suppressing S100A8/9 and MMP9 expression in lung tissue, thereby reducing neutrophil recruitment and spontaneous migration from the bone marrow.

IL-37 Isoform A Prevents Collagen-Induced Arthritis in Mice by Modulating the Th17/Treg Balance via IL1R8 Receptors

Cytokines play a complex and pivotal role in modulating synovitis in rheumatoid arthritis. Interleukin (IL)-37 is known for its extensive anti-inflammatory properties that set it apart from the majority of other IL-1 family members. However, IL-37a, a member of the IL-37 family, lacks research into rheumatoid arthritis. This research aims to explore the role of IL-37a in regulating T-cell homeostasis in rheumatoid arthritis using the Collagen-Induced Arthritis(CIA) model. IL-37atg mice, a genetically altered strain carrying the human IL-37a gene, were used to test the influence of this cytokine on the progression of arthritis. The results show that IL-37atg mice demonstrated a notable reduction in both the incidence and severity of arthritis relative to WT mice. The protective effect was accompanied by lower levels of cytokines in plasma and synovial tissues (such as IL-17A and IL1β) that drive the inflammatory response. The ratio of Th17/Treg decreased in the lymph nodes of IL-37atg mice. However, the knockout of IL1R8 in IL37atg mice eliminated the effects of IL-37a. Additionally, transcriptomic analysis revealed that Th17 cell differentiation is a key pathway through which IL-37a exerts its protective effects, and experiments confirmed that IL-37a suppresses Th17-polarizing in vitro.

IL-37 suppresses CNS autoimmunity by increasing the frequency of Treg cells and reducing CD4 + T cell-derived IL-10 production

BACKGROUND

Interleukin-37 (IL-37) has anti-inflammatory properties in innate and adaptive immunity. Patients with multiple sclerosis (MS), an autoimmune inflammatory demyelinating disease of the central nervous system (CNS), have increased serum levels of IL-37. However, it is unknown whether IL-37 has an inhibitory effect on ongoing autoimmune neuroinflammation, thus offering a potential MS therapy.

AIM

Here, we examined the effect of IL-37 in an experimental autoimmune encephalomyelitis (EAE) model after disease onset to determine if it was protective.

FINDINGS

IL-37-treated mice developed a less severe disease than control mice, with reduced demyelination as determined by increased expression of myelin basic protein. IL-37 suppressed inflammation by decreasing infiltration of CD4 + T cells into the CNS and increasing the frequency of regulatory T cells, while IL-10 expression by CD4 + T cells decreased over time in the CNS.

CONCLUSION

Our findings confirm the immunomodulatory role of IL-37 in CNS inflammation during ongoing disease, thus indicating the potential of IL-37 as an inhibitory reagent for MS therapy.

Insights into the multifaceted role of interleukin-37 on human immune cell regulation

Autoinflammatory diseases, while having a variety of underlying causes, are mediated by dysfunctional innate immune responses. Therefore, standard treatments target innate cytokines or block their receptors. Despite excellent responses in some patients, first-line treatments fail in others, for reasons which remain to be understood. We studied the effects of IL-37, an anti-inflammatory cytokine, on immune cells using multi-omics profiling of 325 healthy adults. Our findings show that IL-37 is associated with inflammation control and generally reduced immune cell activity. Further, genetic variants in IL37 are associated with impaired trained immunity, a memory phenotype of innate immune cells contributing to autoinflammation. To underpin the medical potential of IL-37, an explorative cohort of seven autoinflammatory disorders was built. In vitro stimulation experiments argue for recombinant IL-37 as a potential therapy in IL-6-, and IL-22-driven conditions. Concluding, IL-37 is highlighted as a cytokine with broad anti-inflammatory functions, implicating its potential as therapeutic intervention.

Potential pro-tumour cytokine in oral squamous cellular carcinoma: IL37

Inflammation and immunosuppression are important features of tumours, including oral squamous cellular carcinoma (OSCC). Interleukin 37 (IL37), a cytokine known for the ability to suppress inflammation and immunity, shows two seemingly contradictory functions in tumours. This study aims to investigate the mechanism that regulates IL37 and its role in OSCC progression. Herein, IL37, CD86 and CD206 in OSCC specimens were determined. Hypoxia, MCC950 and siRNA-Gasdermin D (GSDMD) were utilised to investigate the mechanism of IL37 production and release. Animal experiments were established to examine the role of IL37 in OSCC growth in vivo. We found the levels of IL37 are elevated in OSCC tissues compared with normal oral mucosa. In cell experiments, hypoxia was proved to be a vital facilitator in IL37 expression and release. Mechanically, hypoxia promoted IL37 expression through the activation of NACHT-LRR-PYD-containing protein 3 (NLRP3) inflammasome, and promoted IL37 release via GSDMD. Furthermore, IL37 levels in OSCC specimens are positively correlated with the number of M2 macrophages, but negatively with M1. Further studies revealed IL37 facilitated OSCC progression via promoting macrophage polarization from M1 to M2 and enhancing tumour cell proliferation. Thus, IL37 could be a promising target for OSCC treatment in the future.

Interleukin 37 inhibits the migration and invasion of Glioma cells

Glioma is a medical term that describes a tumor originating in the brain. Several risk factors could develop glioma such as occupational exposure, gene mutation and ionizing radiation. Therefore, we aim to determine the expression and biological function of interleukin 37 (IL-37) in gliomas with different pathological grades. We used 95 participants with different pathological grades of glioma as our data subjects. We used CCK-8 assay and transwell assay to explore the proliferation of U251 over-expressing IL-37 and migration and invasion of U251. We found that IL-37 expression in tumor tissues was significantly higher than in normal tissue. The reduced IL-37 expression in gliomas was significantly associated with a higher WHO grade and lower Karnofsky Performance Status score. IL-37 expression in glioma tissues showed a decline with the increase of the WHO glioma grade. Patients with low IL-37 expression showed a shorter median survival. Transwell assay indicated that migration and invasion of U251 over-expressing IL-37 was significantly lower than that of the control at 24 h. Our findings showed that low IL-37 expression was negatively correlated with pathological grade and was positively correlated with survival time.

TIR8 protects against nonalcoholic steatohepatitis by antagonizing lipotoxicity-induced PPARα downregulation and reducing the sensitivity of hepatocytes to LPS

In up to one-third of nonalcoholic fatty liver disease (NAFLD) patients, simple steatosis progresses to its more severe form, nonalcoholic steatohepatitis (NASH), but the precise mechanisms underlying this transition are not fully understood. Toll/interleukin-1 receptor 8 (TIR8), a conventional innate immune regulator highly expressed in hepatic tissue, has shown potential for ameliorating various inflammation-related disorders. However, its role in NASH pathogenesis, especially its regulatory effects on lipid metabolism and inflammatory responses, is still unclear. Here, using a TIR8 knockout (TIR8KO) mouse model and mass spectrometry analyses, we found that TIR8KO mice displayed aggravated hepatic steatosis and inflammation, whereas TIR8 overexpression attenuated these adverse effects. Ectopic TIR8 expression counteracts free fatty acid (FFA)-induced PPARα inhibition and downstream signaling. A decrease in TIR8 levels in hepatocytes heightened lipopolysaccharide (LPS) sensitivity. Notably, FFA stimulation led to a direct interaction between TIR8 and proteasome subunit alpha type 4 (PSMA4), facilitating TIR8 degradation. These results revealed that TIR8 safeguards PPARα-regulated lipid metabolism and mitigates inflammation induced by external factors during NASH progression. Our study highlights TIR8 as a promising target for NASH therapy, indicating the potential of TIR8 agonists in treatment strategies.

CM, M UE, V.J. BB. Hepatic schistosomiasis as a determining factor in the development of hepatic granulomas and liver fibrosis: a review of the current literature

Hepatic schistosomiasis is a neglected parasitosis that affects millions of people each year worldwide and leads to high healthcare costs and increased morbidity and mortality in infected humans. It is a disease that has been widely studied in terms of its pathophysiology; therefore, the signaling pathways that lead to liver damage, with the consequent development of liver fibrosis, are now better understood. Research has elucidated the role of soluble egg antigen in the development of hepatic granulomas and liver fibrosis, the signal transducer and activator of transcription 3 and its participation in liver damage, the role of heat shock protein 47 and its involvement in liver fibrosis, the anti-inflammatory effects caused by interleukin-37, and the role of natural killer and natural killer T cells in the development of the disease. Hepatic schistosomiasis can range from simple hepatomegaly to the development of portal hypertension combined with hepatic fibrosis. For diagnostic purposes, a microscopic examination of excreta remains the gold standard; however, abdominal ultrasound has recently taken on an important role in the assessment of liver lesions produced by the parasite. Praziquantel is considered the management drug of choice, and has been associated with a potential preventive antifibrotic effect.

IL-37 protects against house dust mite-induced airway inflammation and airway epithelial barrier dysfunction via inhibiting store-operated calcium entry

BACKGROUND

Airway epithelial barrier dysfunction has been proved to contribute to the development of type 2 inflammation of asthma. Interleukin (IL)-37 is a negative regulator of immune responses and allergic airway inflammation. However, whether IL-37 has any effect on airway epithelial barrier has been unknown.

METHODS

We evaluated the role of IL-37 in both mouse model and cultured 16HBE cells. Histology and ELISA assays were used to evaluate airway inflammation. FITC-dextran permeability assay was used to evaluate the airway epithelial barrier function. Immunofluorescence, western blot and quantitative Real-Time PCR (RT-PCR) were used to evaluate the distribution and expression of tight junction proteins. RT-PCR and Ca2+ fluorescence measurement were used to evaluate the mRNA expression and activity of store-operated calcium entry (SOCE).

RESULTS

IL-37 inhibited house dust mite (HDM)-induced airway inflammation and decreased the levels of IgE in serum and type 2 cytokines in bronchoalveolar lavage fluid (BALF) compared to asthmatic mice. IL-37 protected against HDM-induced airway epithelial barrier dysfunction, including reduced leakage of FITC-dextran, enhanced expression of TJ proteins, and restored the membrane distribution of TJ proteins. Moreover, IL-37 decreased the level of IL-33 in the BALF of asthmatic mice and the supernatants of HDM-treated 16HBE cells. IL-37 decreased the peak level of Ca2+ fluorescence induced by thapsigargin and HDM, and inhibited the mRNA expression of Orai1, suggesting an inhibiting effect of IL-37 on SOCE in airway epithelial cells.

CONCLUSION

IL-37 plays a protective role in airway inflammation and HDM-induced airway epithelial barrier dysfunction by inhibiting SOCE.

New insights gained from cellular landscape changes in myocarditis and inflammatory cardiomyopathy

Advances in the etiological classification of myocarditis and inflammatory cardiomyopathy (ICM) have reached a consensus. However, the mechanism of myocarditis/ICM remains unclear, which affects the development of treatment and the improvement of outcome. Cellular transcription and metabolic reprogramming, and the interactions between cardiomyocytes and non-cardiomyocytes, such as the immune cells, contribute to the process of myocarditis/ICM. Recent efforts have been made by multi-omics techniques, particularly in single-cell RNA sequencing, to gain a better understanding of the cellular landscape alteration occurring in disease during the progression. This article aims to provide a comprehensive overview of the latest studies in myocarditis/ICM, particularly as revealed by single-cell sequencing.

Inflammatory cytokine signalling in vulvovaginal candidiasis: a hot mess driving immunopathology

Protective immunity to opportunistic fungal infections consists of tightly regulated innate and adaptive immune responses that clear the infection. Immune responses to infections of the vaginal mucosa by Candida species are, however, an exception. In the case of vulvovaginal candidiasis (VVC), the inflammatory response is associated with symptomatic disease, rather than that it results in pathogen clearance. As such VVC can be considered an inflammatory disease, which is a significant public health problem due to its predominance as a female-specific fungal infection. Particularly, women with recurrent VVC (RVVC) suffer from a significant negative impact on their quality of life and mental health. Knowledge of the inflammatory pathogenesis of (R)VVC may guide more effective diagnostic and therapeutic options to improve the quality of life of women with (R)VVC. Here, we review the immunopathogenesis of (R)VVC describing several elements that induce an inflammatory arson, starting with the activation threshold established by vaginal epithelial cells that prevent unnecessary ignition of inflammatory responses, epithelial and inflammasome-dependent immune responses. These inflammatory responses will drive neutrophil recruitment and dysfunctional neutrophil-mediated inflammation. We also review the, sometimes controversial, findings on the involvement of adaptive and systemic responses. Finally, we provide future perspectives on the potential of some unexplored cytokine axes and discuss whether VVC needs to be subdivided into subgroups to improve diagnosis and treatment.

The role of IL-37 in gastrointestinal diseases

Gastrointestinal mucosal surface is frequently under challenge due to it's the large surface area and most common entry of microbes. IL-37, an anti-inflammatory cytokine, regulates local and systemic host immunity. H. pylori infection leads to the inhibition of IL-37 in the gastric mucosa, contributing to heightened mucosal inflammation and destruction, thereby facilitating increased proliferation of H. pylori. Food allergy, due to immune dysregulation, also contribute to GI injury. On the other hand, elevated levels of IL-37 observed in gastric cancer patients align with reduced host immunity at the cellular and humoral levels, indicating that IL-37 may contribute to the development of gastric cancer via suppressing pro-inflammatory responses. While IL-37 provides protection in an IBD animal model, the detection of highly produced IL-37 in IBD patients suggests a stage-dependent role, being protective in acute inflammation but potentially exacerbates the development of IBD in chronic conditions. Moreover, elevated colonic IL-37 in CRC correlates with overall survival time and disease time, indicating a protective role for IL-37 in CRC. The differential regulation and expression of IL-37 between upper- and lower-GI organs may be attributed to variations in the microbial flora. This information suggests that IL-37 could be a potential therapeutic agent, depending on the stage and location.

Comprehensive Insights into Keloid Pathogenesis and Advanced Therapeutic Strategies

Keloid scars, characterized by abnormal fibroproliferation and excessive extracellular matrix (ECM) production that extends beyond the original wound, often cause pruritus, pain, and hyperpigmentation, significantly impacting the quality of life. Keloid pathogenesis is multifactorial, involving genetic predisposition, immune response dysregulation, and aberrant wound-healing processes. Central molecular pathways such as TGF-β/Smad and JAK/STAT are important in keloid formation by sustaining fibroblast activation and ECM deposition. Conventional treatments, including surgical excision, radiation, laser therapies, and intralesional injections, yield variable success but are limited by high recurrence rates and potential adverse effects. Emerging therapies targeting specific immune pathways, small molecule inhibitors, RNA interference, and mesenchymal stem cells show promise in disrupting the underlying mechanisms of keloid pathogenesis, potentially offering more effective and lasting treatment outcomes. Despite advancements, further research is essential to fully elucidate the precise mechanisms of keloid formation and to develop targeted therapies. Ongoing clinical trials and research efforts are vital for translating these scientific insights into practical treatments that can markedly enhance the quality of life for individuals affected by keloid scars.

The role of IL-1 family of cytokines in the pathogenesis and therapy of Alzheimer's disease

Alzheimer's disease (AD) is a progressive and irreversible neurological condition that occurs with age and poses a significant global public health concern, is distinguished by the degeneration of neurons and synapses in various regions of the brain. While the exact processes behind the neurodegeneration in AD are not completely known, it is now acknowledged that inflammation may have a significant impact on the beginning and advancement of AD neurodegeneration. The severity of many neurological illnesses can be influenced by the equilibrium between pro-inflammatory and anti-inflammatory mediators. The IL-1 family of cytokines is linked to innate immune responses, which are present in both acute inflammation and chronic inflammatory diseases. Research on the role of the IL-1 family in chronic neurological disease has been concentrated on AD. In this context, there is indirect evidence suggesting its involvement in the development of the disease. This review aims to provide a summary of the contribution of every IL-1 family member in AD pathogenesis, current immunotherapies in AD disease, and present treatment possibilities for either targeting or boosting these cytokines.

A Narrative Review of the IL-18 and IL-37 Implications in the Pathogenesis of Atopic Dermatitis and Psoriasis: Prospective Treatment Targets

Atopic dermatitis and psoriasis are prevalent inflammatory skin conditions that significantly impact the quality of life of patients, with diverse treatment options available. Despite advances in understanding their underlying mechanisms, recent research highlights the significance of interleukins IL-18 and IL-37, in Th1, Th2, and Th17 inflammatory responses, closely associated with the pathogenesis of psoriasis and atopic dermatitis. Hence, IL-18 and IL-37 could potentially become therapeutic targets. This narrative review synthesizes knowledge on these interleukins, their roles in atopic dermatitis and psoriasis, and emerging treatment strategies. Findings of a literature search up to 30 May 2024, underscore a research gap in IL-37-targeted therapies. Conversely, IL-18-focused treatments have demonstrated promise in adult-onset Still's Disease, warranting further exploration for their potential efficacy in psoriasis and atopic dermatitis.

Insights into IL-1 family cytokines in kidney allograft transplantation: IL-18BP and free IL-18 as emerging biomarkers

Proinflammatory cytokines and their inhibitors are involved in the regulation of multiple immune reactions including response to transplanted organs. In this prospective study, we evaluated changes in serum concentrations of six IL-1 family cytokines (IL-1 alpha, IL-1 beta, IL-1RA, IL-18, IL-18BP, and IL-36 beta) in 138 kidney allograft recipients and 48 healthy donors. Samples were collected before transplantation and then after one week, three months and one year, additional sera were obtained at the day of biopsy positive for acute rejection. We have shown, that concentrations of proinflammatory members of the IL-1 family (IL-1β, IL-18, IL-36 β) and anti-inflammatory IL-18BP decreased immediately after the transplantation. The decline of serum IL-1RA and IL-1α was not observed in subjects with acute rejection. IL-18, including specifically its free form, is the only cytokine which increase serum concentrations in the period between one week and three months in both groups of patients without upregulation of its inhibitor, IL-18BP. Serum concentrations of calculated free IL-18 were upregulated in the acute rejection group at the time of acute rejection. We conclude that IL-1 family cytokines are involved mainly in early phases of the response to kidney allograft. Serum concentrations of free IL-18 and IL-18BP represent possible biomarkers of acute rejection, and targeting IL-18 might be of therapeutic value.

3-methyl-1H-indol-1-yl dimethylcarbamodithioate attenuates periodontitis through targeting MAPK signaling pathway-regulated mitochondrial function

Periodontitis, the second most common oral disease, is primarily initiated by inflammatory responses and osteoclast differentiation, in which the MAPK signaling pathway and mitochondrial function play important roles. 3-methyl-1H-indol-1-yl dimethylcarbamodithioate (3o), a hybrid of indole and dithiocarbamate, was first synthesized by our group. It has shown anti-inflammatory activity against lipopolysaccharide-induced acute lung injury. However, it is not known if 3o can exert effects in periodontitis. In vitro study: LPS-induced macrophage inflammation initiation and a receptor activator of nuclear factor κB ligand-stimulated osteoclast differentiation model were established. Cell viability, inflammatory cytokines, osteoclast differentiation, the MAPK signaling pathway, and mitochondrial function before and after treatment with 3o were investigated. In vivo study: Alveolar bone resorption, inflammatory cytokine expression, osteoclast differentiation, and the underlying mechanisms were assessed in mice with periodontitis. Inflammatory cytokine expression and osteoclast differentiation appeared downregulated after 3o treatment. 3o inhibited the MAPK signaling pathway and restored mitochondrial function, including mitochondrial reactive oxygen species, mitochondrial membrane potential, and ATP production. Meanwhile, 3o reduced inflammation activation and bone resorption in mice with periodontitis, reflected by the decreased expression of inflammatory cytokines and osteoclasts, implying that 3o inhibited the MAPK signaling pathway and the mitochondrial oxidative DNA damage marker 8-OHdG. These results highlight the protective role of 3o in periodontitis in mice and reveal an important strategy for preventing periodontitis.

IL-37d suppresses Rheb-mTORC1 axis independently of TCS2 to alleviate alcoholic liver disease

Tuberous sclerosis complex 2 (TSC2) crucially suppresses Rheb activity to prevent mTORC1 activation. However, mutations in TSC genes lead to mTORC1 overactivation, thereby causing various developmental disorders and cancer. Therefore, the discovery of novel Rheb inhibitors is vital to prevent mTOR overactivation. Here, we reveals that the anti-inflammatory cytokine IL-37d can bind to lysosomal Rheb and suppress its activity independent of TSC2, thereby preventing mTORC1 activation. The binding of IL-37d to Rheb switch-II subregion destabilizes the Rheb-mTOR and mTOR-S6K interactions, further halting mTORC1 signaling. Unlike TSC2, IL-37d is reduced under ethanol stimulation, which results in mitigating the suppression of lysosomal Rheb-mTORC1 activity. Consequently, the recombinant human IL-37d protein (rh-IL-37d) with a TAT peptide greatly improves alcohol-induced liver disorders by hindering Rheb-mTORC1 axis overactivation in a TSC2- independent manner. Together, IL-37d emerges as a novel Rheb suppressor independent of TSC2 to terminate mTORC1 activation and improve abnormal lipid metabolism in the liver.

Neutrophil-derived nanovesicles deliver IL-37 to mitigate renal ischemia-reperfusion injury via endothelial cell targeting

Renal ischemia-reperfusion injury (IRI) is one of the most important causes of acute kidney injury (AKI). Interleukin (IL)-37 has been suggested as a novel anti-inflammatory factor for the treatment of IRI, but its application is still limited by its low stability and delivery efficiency. In this study, we reported a novel engineered method to efficiently and easily prepare neutrophil membrane-derived vesicles (N-MVs), which could be utilized as a promising vehicle to deliver IL-37 and avoid the potential side effects of neutrophil-derived natural extracellular vesicles. N-MVs could enhance the stability of IL-37 and targetedly deliver IL-37 to damaged endothelial cells of IRI kidneys via P-selectin glycoprotein ligand-1 (PSGL-1). In vitro and in vivo evidence revealed that N-MVs encapsulated with IL-37 (N-MV@IL-37) could inhibit endothelial cell apoptosis, promote endothelial cell proliferation and angiogenesis, and decrease inflammatory factor production and leukocyte infiltration, thereby ameliorating renal IRI. Our study establishes a promising delivery vehicle for the treatment of renal IRI and other endothelial damage-related diseases.

Important Roles of Interleukin-36, Interleukin-37, and Interleukin-38 Cytokines in the Pathogenesis of Rosacea

Background

Rosacea is a chronic inflammatory skin disease. Previous studies have determined that IL-36, IL-37, and IL-38 may play a role in the pathogenesis of various inflammatory diseases.

Aims and Objectives

The present study aims to evaluate the relationship of these cytokines with rosacea.

Materials and Methods

A total of 100 individuals, including 50 patients with rosacea and 50 healthy controls, were included in the study. IL-36, IL-37, and IL-38 levels were measured using the ELISA method by taking serum samples from all participants.

Results

The mean serum levels of IL-36, IL-37, and IL-38 in the patient group were 52.17 ± 24.07 pg/ml, 18.46 ± 8.18 pg/ml, and 25.74 ± 8.36 ng/l, respectively. The mean serum levels of IL-36, IL-37, and IL-38 in the control group were 32.99 ± 19.90 pg/ml, 44.61 ± 22.27 pg/ml, and 45.61 ± 17.32 ng/l, respectively. The difference between the serum levels of IL-36, IL-37, and IL-38 in the patient and control groups was statistically significant (P < 0.001).

Conclusion

Based on these findings, an increase in IL-36 and a decrease in IL-37 and IL-38 may contribute to the pathogenesis of rosacea. Future rosacea treatments could target and/or interact with these possible steps in the pathogenesis of rosacea.

Immune System Dysregulation in the Progression of Multiple Sclerosis: Molecular Insights and Therapeutic Implications

Multiple sclerosis (MS), a prevalent neurological disorder, predominantly affects young adults and is characterized by chronic autoimmune activity. The study explores the immune system dysregulation in MS, highlighting the crucial roles of immune and non-neuronal cells in the disease's progression. This review examines the dual role of cytokines, with some like IL-6, TNF-α, and interferon-gamma (IFN-γ) promoting inflammation and CNS tissue injury, and others such as IL-4, IL-10, IL-37, and TGF-β fostering remyelination and protecting against MS. Elevated chemokine levels in the cerebrospinal fluid (CSF), including CCL2, CCL5, CXCL10, CXCL13, and fractalkine, are analyzed for their role in facilitating immune cell migration across the blood-brain barrier (BBB), worsening inflammation and neurodegeneration. The study also delves into the impact of auto-antibodies targeting myelin components like MOG and AQP4, which activate complement cascades leading to further myelin destruction. The article discusses how compromised BBB integrity allows immune cells and inflammatory mediators to infiltrate the CNS, intensifying MS symptoms. It also examines the involvement of astrocytes, microglia, and oligodendrocytes in the disease's progression. Additionally, the effectiveness of immunomodulatory drugs such as IFN-β and CD20-targeting monoclonal antibodies (e.g., rituximab) in modulating immune responses is reviewed, highlighting their potential to reduce relapse rates and delaying MS progression. These insights emphasize the importance of immune system dysfunction in MS development and progression, guiding the development of new therapeutic strategies. The study underscores recent advancements in understanding MS's molecular pathways, opening avenues for more targeted and effective treatments.

Innate Immunity and MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) has emerged as the most common liver disease worldwide in recent years. MASLD commonly presents as simple hepatic steatosis, but ~25% of patients develop liver inflammation, progressive fibrosis, liver cirrhosis and related hepatocellular carcinoma. Liver inflammation and the degree of fibrosis are key determinants of the prognosis. The pathophysiology of liver inflammation is incompletely understood and involves diverse factors and specifically innate and adaptive immune responses. More specifically, diverse mediators of innate immunity such as proinflammatory cytokines, adipokines, inflammasomes and various cell types like mononuclear cells, macrophages and natural killer cells are involved in directing the inflammatory process in MASLD. The activation of innate immunity is driven by various factors including excess lipids and lipotoxicity, insulin resistance and molecular patterns derived from gut commensals. Targeting pathways of innate immunity might therefore appear as an attractive therapeutic strategy in the future management of MASLD and possibly its complications.

Modulating inflammation with interleukin 37 treatment ameliorates murine Autosomal Dominant Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a leading cause of kidney failure and is associated with substantial morbidity and mortality. Interstitial inflammation is attributed to the action of infiltrating macrophages and is a feature thought to aggravate disease progression. Here, we investigated the therapeutic potential of the anti-inflammatory IL37b cytokine as a treatment for ADPKD using genetic mouse models, demonstrating that transgenic expression of human IL37b reduced collecting duct cyst burden in both early and adult-onset ADPKD rodent models. Moreover, injection of recombinant human IL37b could also reduce cyst burden in early onset ADPKD mice, an observation not associated with increased macrophage number at early stages of cyst formation. Interestingly, transgenic IL37b expression also did not alter macrophage numbers in advanced disease. Whole kidney RNA-seq highlighted an IL37b-mediated upregulation of the interferon signaling pathway and single-cell RNA-seq established that these changes originate at least partly from kidney resident macrophages. We further found that blocking type I interferon signaling in mice expressing IL37b resulted in increased cyst number, confirming this as an important pathway by which IL37b exerts its beneficial effects. Thus, our studies show that IL37b promotes interferon signaling in kidney resident macrophages which suppresses cyst initiation, identifying this protein as a potential therapy for ADPKD.

IL-37 dampens immunosuppressive functions of MDSCs via metabolic reprogramming in the tumor microenvironment

Interleukin-37 (IL-37) has been shown to inhibit tumor growth in various cancer types. However, the immune regulatory function of IL-37 in the tumor microenvironment is unclear. Here, we established a human leukocyte antigen-I (HLA-I)-matched humanized patient-derived xenograft hepatocellular carcinoma (HCC) model and three murine orthotopic HCC models to study the function of IL-37 in the tumor microenvironment. We found that IL-37 inhibited HCC growth and promoted T cell activation. Further study revealed that IL-37 impaired the immunosuppressive capacity of myeloid-derived suppressor cells (MDSCs). Pretreatment of MDSCs with IL-37 before adoptive transfer attenuated their tumor-promoting function in HCC tumor-bearing mice. Moreover, IL-37 promoted both glycolysis and oxidative phosphorylation in MDSCs, resulting in the upregulation of ATP release, which impaired the immunosuppressive capacity of MDSCs. Collectively, we demonstrated that IL-37 inhibited tumor development through dampening MDSCs' immunosuppressive capacity in the tumor microenvironment via metabolic reprogramming, making it a promising target for future cancer immunotherapy.

IL-37d enhances COP1-mediated C/EBPβ degradation to suppress spontaneous neutrophil migration and tumor progression

The spontaneous migration of bone marrow neutrophils (BMNs) is typically induced by distant tumor cells during the early stage of the tumor and critically controls tumor progression and metastases. Therefore, identifying the key molecule that prevents this process is extremely important for suppressing tumors. Interleukin-37 (IL-37) can suppress pro-inflammatory cytokine generation via an IL-1R8- or Smad3-mediated pathway. Here, we demonstrate that human neutrophil IL-37 is responsively reduced by tumor cells and the recombinant IL-37 isoform d (IL-37d) significantly inhibits spontaneous BMN migration and tumor lesion formation in the lung by negatively modulating CCAAT/enhancer binding protein beta (C/EBPβ) in a Lewis lung carcinoma (LLC)-inducing lung cancer mouse model. Mechanistically, IL-37d promotes C/EBPβ ubiquitination degradation by facilitating ubiquitin ligase COP1 recruitment and disrupts C/EBPβ DNA binding abilities, thereby reducing neutrophil ATP generation and migration. Our work reveals an anti-tumor mechanism for IL-37 via destabilization of C/EBPβ to prevent spontaneous BMN migration and tumor progression.

Agree to disagree: The contradiction between IL-18 and IL-37 reveals shared targets in cancer

IL-37 is a newly discovered member of the IL-1 cytokine family which plays an important role in regulating inflammation and maintaining physiological homeostasis. IL-37 showed a close relationship with IL-18, another key cytokine in inflammation regulation and cancer development. IL-37 affects the function of IL-18 either by binding to IL-18Rα, a key subunit of both IL-37 and IL-18 receptor, or by drastically neutralizing the IL-18 protein expression of IL-18 binding protein, an important natural inhibitory molecule of IL-18. Moreover, as another subunit receptor of IL-37, IL-1R8 can suppress IL-18Rα expression, functioning as a surveillance mechanism to prevent overactivation of both IL-18 and IL-37 signaling pathways. While IL-18 and IL-37 share the same receptor subunit, IL-18 would in turn interfere with IL-37 signal transduction by binding to IL-18Rα. It is also reported that IL-18 and IL-37 demonstrated opposing effects in a variety of cancers, such as glioblastoma, lung cancer, leukemia, and hepatocellular cancer. Although the mutual regulation of IL-18 and IL-37 and their diametrically opposed effects in cancers has been reported, IL-18 has not been taken into consideration when interpreting clinical findings and conducting mechanism investigations related to IL-37 in cancer. We aim to review the recent progress in IL-18 and IL-37 research in cancer and summarize the correlation between IL-18 and IL-37 in cancer based on their expression level and underlying mechanisms, which would provide new insights into elucidating the conflicting roles of IL-18 and IL-37 in cancer and bring new ideas for translational research related to IL-18 and IL-37.

D-Mannose promotes recovery from experimental colitis by inducing AMPK phosphorylation to stimulate epithelial repair

Delayed mucosal healing and impaired intestinal epithelial barrier function have been implicated in the pathogenesis of ulcerative colitis (UC). Accordingly, restoration of epithelial barrier function as a means to reshape mucosal homeostasis represents an important strategy for use in the treatment of UC. In this study, we examined the role and mechanisms of D-mannose in the recovery of colitis as assessed in both animal and cell models. We found that D-mannose ameliorated inflammation, promoted mucosal healing in the colon and therefore was able to induce the recovery of UC. Furthermore, D-mannose increased the expression of tight junction (TJ) proteins and reduced the intestinal permeability during the recovery of colitis. Moreover, D-mannose inhibited M1 macrophage polarization and promoted M2 macrophage polarization via inducing AMPK phosphorylation while reducing mTOR phosphorylation in both models. In addition, increased TJ protein expression and decreased paracellular permeability were observed in NCM460 cells when incubated with the supernatants of D-mannose-treated RAW264.7 cells, suggesting that M1/M2 polarization induced by D-mannose modulates the expression of TJ proteins. Further study showed that D-mannose significantly upregulated the expression of TJ proteins in DSS-treated NCM460 cells by inducing AMPK phosphorylation, indicating a direct protective effect on epithelial cells. Finally, the protective effects of D-mannose were significantly abrogated by the presence of compound C, an AMPK inhibitor. Taken together, our data indicate that D-mannose can alleviate inflammation and foster epithelial restitution in UC recovery by inducing the TJ protein expression, which are achieved by inducing AMPK phosphorylation in the epithelium and/or macrophages.

The role of IL-36 and 37 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has garnered considerable attention due to its morbidity and mortality. Although the precise mechanisms underlying HCC tumorigenesis remain to be elucidated, evidence suggests that host immunity plays a pivotal role in its development. IL-36 and IL-37 are important immunoregulatory cytokines classified as pro-inflammatory and anti-inflammatory respectively. In the context of HCC, the downregulation of intrahepatic IL-36 is inversely correlated with cirrhosis, but positively correlated with 5-year survival rates, suggesting that IL-36 offers protection during HCC development. However, IL-36 may lose its hepatoprotective effects as the disease progresses to HCC in the context of dysregulated immunity in cirrhotic patients. Substantially increased circulating IL-36 in HCC patients is likely a systemic response to HCC stimulation, but is insufficient to suppress progression towards HCC. Intrahepatic IL-37 is suppressed in HCC patients, consistent with the inverse correlation between intrahepatic IL-37 and the level of AFP in HCC patients, suggesting IL-37 exerts hepatoprotection. There is no significant difference in IL-37 among differentiations of HCC or with respect to clinical BCLC stages or cirrhosis status in HCC patients. However, IL-37 protection is demonstrated in an IL-37 transfected HCC animal model, showing significantly reduced tumour size. IL-36/37 may inhibit HCC by enhancing M1 tumour-associated macrophages while not affecting M2 macrophages. The interplay between IL-36 (pro-inflammatory) and IL-37 (anti-inflammatory) is emerging as a crucial factor in host protection against the development of HCC. Further research is needed to investigate the complex mechanisms involved and the therapeutic potential of targeting these cytokines in HCC management.

Circulating Interleukins-33 and -37 and Their Associations with Metabolic Syndrome in Arab Adults

Interleukins (ILs) are a group of cytokines known to have immunomodulatory effects; they include ILs-33 and -37 whose emerging roles in the pathogenesis of metabolic syndrome (MetS) remain under investigated. In this study, we compared circulating IL-33 and IL-37 in Arab adults with and without MetS to determine its associations with MetS components. A total of 417 Saudi participants (151 males, 266 females; mean age ± SD 41.3 ± 9.0 years; mean body mass index ± SD 30.7 ± 6.3 kg/m2) were enrolled and screened for MetS using the ATP III criteria. Anthropometrics and fasting blood samples were taken for the assessment of fasting glucose and lipids. Circulating levels of IL-33 and IL-37 were measured using commercially available assays. The results showed higher levels of serum IL-33 and IL-37 in participants with MetS than those without (IL-33, 3.34 3.42 (2.3-3.9) vs. (1-3.9), p = 0.057; IL-37, 5.1 (2.2-8.3) vs. 2.9 (2.1-6.1), p = 0.01). Additionally, having elevated levels of IL-33 was a risk factor for hypertension, low HDL-c, and hypertriglyceridemia. A stratification of the participants according to sex showed that males had higher IL-33 levels than females [3.7 (3.0-4.1) vs. 3.15 (1.4-3.8), p < 0.001], while females had higher levels of IL-37 than males [3.01 (2.2-7.0) vs. 2.9 (2.1-5.6), p = 0.06]. In conclusion, the presence of MetS substantially alters the expression of ILs-33 and -37. IL-33 in particular can be potentially used as a therapeutic target to prevent MetS progression. Longitudinal and interventional studies are warranted to confirm present findings.

Interleukin-37 relieves PM2.5-triggered lung injury by inhibiting autophagy through the AKT/mTOR signaling pathway in vivo and in vitro

Autophagy mediates PM2.5-related lung injury (LI) and is tightly linked to inflammation and apoptosis processes. IL-37 has been demonstrated to regulate autophagy. This research aimed to examine the involvement of IL-37 in the progression of PM2.5-related LI and assess whether autophagy serves as a mediator for its effects.To create a model of PM2.5-related LI, this research employed a nose-only PM2.5 exposure system and utilized both human IL-37 transgenic mice and wild-type mice. The hIL-37tg mice demonstrated remarkable reductions in pulmonary inflammation and pathological LI compared to the WT mice. Additionally, they exhibited activation of the AKT/mTOR signaling pathway, which served to regulate the levels of autophagy and apoptosis.Furthermore, in vitro experiments revealed a dose-dependent upregulation of autophagy and apoptotic proteins following exposure to PM2.5 DMSO extraction. Simultaneously, p-AKT and p-mTOR expression was found to decrease. However, pretreatment with IL-37 demonstrated a remarkable reduction in the levels of autophagy and apoptotic proteins, along with an elevation of p-AKT and p-mTOR. Interestingly, pretreatment with rapamycin, an autophagy inducer, weakened the therapeutic impact of IL-37. Conversely, the therapeutic impact of IL-37 was enhanced when treated with 3-MA, a potent autophagy inhibitor. Moreover, the inhibitory effect of IL-37 on autophagy was successfully reversed by administering AKT inhibitor MK2206. The findings suggest that IL-37 can inhibit both the inflammatory response and autophagy, leading to the alleviation of PM2.5-related LI. At the molecular level, IL-37 may exert its anti autophagy and anti apoptosis effects by activating the AKT/mTOR signaling pathway.

Potential Role of IL-37 in Atopic Dermatitis

Interleukin 37 (IL-37) is a recently discovered member of the IL-1 cytokine family that appears to have anti-inflammatory and immunosuppressive effects in various diseases. IL-37 acts as a dual-function cytokine, exerting its effect extracellularly by forming a complex with the receptors IL-18 α (IL-18Rα) and IL-1R8 and transmitting anti-inflammatory signals, as well as intracellularly by interacting with Smad3, entering the nucleus, and inhibiting the transcription of pro-inflammatory genes. Consequently, IL-37 is linked to IL-18, which plays a role in the pathogenesis of atopic dermatitis (AD), consistent with our studies. Some isoforms of IL-37 are expressed by keratinocytes, monocytes, and other skin immune cells. IL-37 has been found to modulate the skewed T helper 2 (Th2) inflammation that is fundamental to the pathogenesis of AD. This review provides an up-to-date summary of the function of IL-37 in modulating the immune system and analyses its potential role in the pathogenesis of AD. Moreover, it speculates on IL-37's hypothetical value as a therapeutic target in the treatment of AD.

IL-38 regulates intestinal stem cell homeostasis by inducing WNT signaling and beneficial IL-1β secretion

The IL-1 Family member IL-38 has been characterized primarily as an antiinflammatory cytokine in human and mouse models of systemic diseases. Here, we examined the role of IL-38 in the murine small intestine (SI). Immunostaining of SI revealed that IL-38 expression partially confines to intestinal stem cells. Cultures of intestinal organoids reveal IL-38 functions as a growth factor by increasing organoid size via inducing WNT3a. In contrast, organoids from IL-38-deficient mice develop more slowly. This reduction in size is likely due to the downregulation of intestinal stemness markers (i.e., Fzd5, Ephb2, and Olfm4) expression compared with wild-type organoids. The IL-38 binding to IL-1R6 and IL-1R9 is still a matter of debate. Therefore, to analyze the molecular mechanisms of IL-38 signaling, we also examined organoids from IL-1R9-deficient mice. Unexpectedly, these organoids, although significantly smaller than wild type, respond to IL-38, suggesting that IL-1R9 is not involved in IL-38 signaling in the stem cell crypt. Nevertheless, silencing of IL-1R6 disabled the organoid response to the growth property of IL-38, thus suggesting IL-1R6 as the main receptor used by IL-38 in the crypt compartment. In organoids from wild-type mice, IL-38 stimulation induced low concentrations of IL-1β which contribute to organoid growth. However, high concentrations of IL-1β have detrimental effects on the cultures that were prevented by treatment with recombinant IL-38. Overall, our data demonstrate an important regulatory function of IL-38 as a growth factor, and as an antiinflammatory molecule in the SI, maintaining homeostasis.

Disturbing cytoskeleton by engineered nanomaterials for enhanced cancer therapeutics

Cytoskeleton plays a significant role in the shape change, migration, movement, adhesion, cytokinesis, and phagocytosis of tumor cells. In clinical practice, some anti-cancer drugs achieve cytoskeletal therapeutic effects by acting on different cytoskeletal protein components. However, in the absence of cell-specific targeting, unnecessary cytoskeletal recombination in organisms would be disastrous, which would also bring about severe side effects during anticancer process. Nanomedicine have been proven to be superior to some small molecule drugs in cancer treatment due to better stability and targeting, and lower side effects. Therefore, this review summarized the recent developments of various nanomaterials disturbing cytoskeleton for enhanced cancer therapeutics, including carbon, noble metals, metal oxides, black phosphorus, calcium, silicon, polymers, peptides, and metal-organic frameworks, etc. A comprehensive analysis of the characteristics of cytoskeleton therapy as well as the future prospects and challenges towards clinical application were also discussed. We aim to drive on this emerging topic through refreshing perspectives based on our own work and what we have also learnt from others. This review will help researchers quickly understand relevant cytoskeletal therapeutic information to further advance the development of cancer nanomedicine.