The Role of the IL-33/ST2 Immune Pathway in Autoimmunity: New Insights and Perspectives

Exploring the Relationship between Serum IL-33 Levels and Clinical Manifestations in Systemic Lupus Erythematosus: A Comprehensive Analysis

Aims/Background Systemic lupus erythematosus (SLE) is a complex autoimmune disorder characterised by an unpredictable disease course and multifaceted clinical presentations. Recent studies have highlighted the potential role of interleukin-33 (IL-33) in autoimmune diseases, but its exact relationship with SLE remains unclear. Therefore, to investigate the role of serum IL-33 levels as a biomarker, we evaluated its correlation with disease activity and organ damage in SLE patients. Methods This retrospective analysis included 120 SLE patients from the Department of Rheumatology and Immunology, The Fourth Affiliated Hospital of Soochow University between January 2018 and December 2022. For comparative analysis, we recruited 60 healthy controls. Correlations between IL-33 levels and disease metrics were evaluated, and subgroup analyses were performed to explore specific clinical associations. Results Our findings revealed that SLE patients had significantly higher serum IL-33 levels than the control group (258.7 ± 103.5 pg/mL vs 78.3 ± 32.6 pg/mL, p < 0.001). Furthermore, IL-33 levels showed a significant association with both disease activity (Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)) (r = 0.68, p < 0.001) and cumulative organ damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SLICC/ACR DI)) scores (r = 0.45, p < 0.01). Notably, patients with active disease (SLEDAI ≥6) exhibited substantially elevated IL-33 levels (p < 0.001). Patients with organ damage (SLICC/ACR DI ≥1) demonstrated significantly higher IL-33 levels than those without organ damage (289.6 ± 95.3 pg/mL vs 234.1 ± 86.2 pg/mL, p = 0.001), and those with renal involvement showed higher IL-33 levels (p < 0.01). Receiver operating characteristic (ROC) curve analysis revealed better diagnostic potential of serum IL-33 levels for SLE (area under the curve (AUC) = 0.892, 95% confidence interval (CI): 0.845-0.939, sensitivity = 84.2%, specificity = 82.7%) and for identifying active disease (AUC = 0.816, 95% CI: 0.752-0.880, sensitivity = 77.8%, specificity = 75.0%). Conclusion Our findings suggest that serum IL-33 may serve as a promising biomarker for comprehensive SLE assessment, offering new avenues for monitoring disease progression and guiding therapeutic strategies.

Exploring Advances in Natural Plant Molecules for Allergic Rhinitis Immunomodulation in Vivo and in Vitro

Allergic rhinitis (AR) is a prevalent allergic disease that imposes significant economic burdens and life pressures on individuals, families, and society, particularly in the context of accelerating globalization and increasing pathogenic factors. Current clinical therapies for AR include antihistamines, glucocorticoids administered via various routes, leukotriene receptor antagonists, immunotherapy, and several decongestants. These treatments have demonstrated efficacy in alleviating clinical symptoms and pathological states. However, with the growing awareness of AR and rising expectations for improvements in quality of life, these treatments have become associated with a higher incidence of side effects and an elevated risk of drug resistance. Furthermore, the development of AR is intricately associated with dysregulation of the immune system, yet the underlying pathogenetic mechanisms remain incompletely understood. In contrast, widely available natural plant molecules offer multiple targeting pathways that uniquely modify the typical pathophysiology of AR through immunomodulatory processes. This review presents a comprehensive analysis of both in vivo and in vitro studies on natural plant molecules that modulate immunity for treating AR. Additionally, we examine their specific mechanisms of action in animal models to provide new insights for developing safe and effective targeted therapies while guiding experimental and clinical applications against AR.

Reduced autoimmunity associated with deletion of host CD73

CD73 is ubiquitously expressed and regulates critical functions across multiple organ systems. The sequential actions of CD39 and CD73 accomplish the conversion of adenosine triphosphate to adenosine and shift the adenosine triphosphate-driven proinflammatory immune cell milieu toward an anti-inflammatory state. This immunological switch is a major mechanism by which regulatory T (Treg) cells control inflammation. Foxp3 engages in Treg development and function. Foxp3 mutations result in the scurfy (SF) mouse phenotype and a rapidly lethal lymphoproliferative syndrome. We generated double knockout (KO) mouse (CD73KOSF) by breeding heterozygous Foxp3sf/J females to CD73KO male mice to remove host CD73. We initially aimed to use these mice to identify a specific probiotic-CD73 effect, previously shown for Limosilactobacillus reuteri DSM 17938. We expected CD73 deletion to enhance the severity of autoimmunity in SF mice. However, we unexpectedly observed that KO of host CD73 in SF mice clinically reduced the severity of autoimmunity including reduced ear thickness, increased ear size, and less deformed ears, along with less dry and brittle skin. KO of CD73 in SF mice significantly reduced the numbers of CD4+ and CD8+T cells in spleen and blood. We identified that KO of CD73 in SF mice reduced the numbers of T cells in the thymus compared with those in SF mice, indicating that the milder clinical phenotype may be due to reduced central and peripheral lymphoproliferation. These new findings suggest targeting CD73 could improve T cell-mediated dermatitis, one of the most common symptoms in Treg deficiency-associated primary immune deficiencies.

Infertility, IL-17, IL-33 and Microbiome Cross-Talk: The Extended ARIA-MeDALL Hypothesis

Infertility, defined as the inability to obtain pregnancy after 12 months of regular unprotected sexual intercourse, has increased in prevalence over the past decades, similarly to chronic, allergic, autoimmune, or neurodegenerative diseases. A recent ARIA-MeDALL hypothesis has proposed that all these diseases are linked to dysbiosis and to some cytokines such as interleukin 17 (IL-17) and interleukin 33 (IL-33). Our paper suggests that endometriosis, a leading cause of infertility, is linked to endometrial dysbiosis and two key cytokines, IL-17 and IL-33, which interact with intestinal dysbiosis. Intestinal dysbiosis contributes to elevated estrogen levels, a primary factor in endometriosis. Estrogens strongly activate IL-17 and IL-33, supporting the existence of a gut-endometrial axis as a significant contributor to infertility.

Roles of IL-33 in the Pathogenesis of Cardiac Disorders

Interleukin-33 (IL-33) is a member of the IL-1 cytokine family and is believed to play important roles in different diseases by binding to its specific receptor suppression of tumorigenicity 2 (ST2). In the heart, IL-33 is expressed in different cells including cardiomyocytes, fibroblasts, endothelium, and epithelium. Although many studies have been devoted to investigating the effects of IL-33 on heart diseases, its roles in myocardial injuries remain obscure, and thus further studies are mandatory to unravel the underlying molecular mechanisms. We highlighted the current knowledge of the molecular and cellular characteristics of IL-33 and then summarized its major roles in different myocardial injuries, mainly focusing on infection, heart transplantation, coronary atherosclerosis, myocardial infarction, and diabetic cardiomyopathy. This narrative review will summarize current understanding and insights regarding the implications of IL-33 in cardiac diseases and its diagnostic and therapeutic potential for cardiac disease management.

Biological effects of IL-33/ST2 axis on oral diseases: autoimmune diseases and periodontal diseases

IL-33 is a relatively new member of the IL-1 cytokine family, which plays a unique role in autoimmune diseases, particularly some oral diseases dominated by immune factors. The IL-33/ST2 axis is the main pathway by which IL-33 signals affect downstream cells to produce an inflammatory response or tissue repair. As a newly discovered pro-inflammatory cytokine, IL-33 can participate in the pathogenesis of autoimmune oral diseases such as Sjogren's syndrome and Behcet's disease. Moreover, the IL-33/ST2 axis also recruits and activates mast cells in periodontitis, producing inflammatory chemokines and mediating gingival inflammation and alveolar bone destruction. Interestingly, the high expression of IL-33 in the alveolar bone, which exhibits anti-osteoclast effects under appropriate mechanical loading, also confirms its dual role of destruction and repair in an immune-mediated periodontal environment. This study reviewed the biological effects of IL-33 in autoimmune oral diseases, periodontitis and periodontal bone metabolism, and elaborated its potential role and impact as a disease enhancer or a repair factor.

Associations between blood IL-33 levels and IL-33 gene polymorphisms with susceptibility to systemic lupus erythematosus: A meta-analysis

OBJECTIVES

This study investigated the relationship between circulating interleukin-33 (IL-33) levels and systemic lupus erythematosus (SLE) along with polymorphisms in the IL-33 gene and SLE susceptibility.

METHOD

The MEDLINE, EMBASE, and Cochrane Library databases (to May 2023) were searched for relevant publications. Using a meta-analysis we investigated serum/plasma IL-33 levels in patients with SLE and controls, and the relationship between IL-33 rs1929992, rs1891385, rs7044343, rs1095498, and rs10975579 polymorphisms and the risk of developing SLE.

RESULTS

Nine studies focusing on 1,935 patients with SLE were included. IL-33 levels were significantly higher in the SLE group than in the control group (SMD = 2.140, 95% CI = 1.068-3.212, p < .001). Asian, European, and Arab groups have shown increased IL-33 levels in SLE populations, according to ethnic stratification. Regardless of the sample size, variable adjustment, data format, or publication year, the subgroup analysis showed significantly higher IL-33 levels in the SLE group. This meta-analysis supported the significance of the link between SLE and the IL-33 rs1891385 C allele (OR, 1.525; 95% CI, 11.310-1.777; p = .010). A similar association was found between the IL-33 rs1891385 C/A polymorphism and SLE, using homozygote comparisons and dominant and recessive models. However, this meta-analysis found no association between the IL-33 polymorphisms rs1929992, rs7044343, rs1095498, and rs10975579 and susceptibility to SLE.

CONCLUSIONS

This meta-analysis identified significantly higher levels of circulating IL-33 in patients with SLE as well as an association between IL-33 rs1891385 and SLE.

Association of interleukin 33 gene polymorphisms with susceptibility and regulation of inflammatory mediators in Systemic lupus erythematosus patients

BACKGROUND

Studies have indicated the involvement of interleukin (IL)-33 in the pathogenesis of Systemic lupus erythematosus (SLE). This research intended to evaluate the association of IL33 gene rs1929992 and rs7044343 Single nucleotide polymorphisms (SNPs) with risk of SLE. In addition, the association between these SNPs and inflammatory cytokines was determined.

METHODS

In this study, 200 SLE cases and 200 healthy subjects were recruited. Using allelic discrimination Real-time PCR, IL33 gene rs1929992 and rs7044343 SNPs were genotyped. The mRNA expression levels of IL-1β, IL-6, IL-33, TNF-α were determined in the peripheral blood mononuclear cells (PBMCs). The serum levels of cytokines were also measured.

RESULTS

The G allele (OR = 1.57, CI: 1.18-2.08, P = 0.0017), GG genotype (OR = 2.52, CI: 1.33-4.77, P = 0.0043), and GA genotype (OR = 2.12, CI: 1.34-3.34, P = 0.0011) of rs1929992 SNP was significantly associated with an increased SLE risk. The C allele (OR = 1.44, CI: 1.08-1.90; P = 0.0105), CC genotype (OR = 2.07, CI: 1.15-3.71; P = 0.0146), and CT genotype (OR = 1.61, CI: 1.02-2.53, P = 0.0395) of rs7044343 was significantly associated with increased SLE risk. The PBMC mRNA expression and serum levels of IL-1β, IL-6, IL-33, TNF-α were significantly increased in the SLE patients compared to controls. However, there was no significant difference in the mRNA expression and serum levels of IL-1β, IL-6, IL-33, and TNF-α among the SLE patients with three genotypes for both rs1929992 and rs7044343 polymorphisms.

CONCLUSIONS

IL33 gene rs1929992 and rs7044343 SNPs are involved in SLE pathogenesis but they might not influence on the inflammatory pathway.

The IL-33/IL-31 Axis in Allergic and Immune-Mediated Diseases

Interleukin 31 (IL-31) belongs to the IL-6 superfamily [...].

Involvement of Interleukin-1 Receptor-Associated Kinase 4 and Interferon Regulatory Factor 5 in the Immunopathogenesis of SARS-CoV-2 Infection: Implications for the Treatment of COVID-19

Interleukin-1 receptor-associated kinase 4 (IRAK4) and interferon regulatory factor 5 (IRF5) lie sequentially on a signaling pathway activated by ligands of the IL-1 receptor and/or multiple TLRs located either on plasma or endosomal membranes. Activated IRF5, in conjunction with other synergistic transcription factors, notably NF-κB, is crucially required for the production of proinflammatory cytokines in the innate immune response to microbial infection. The IRAK4-IRF5 axis could therefore have a major role in the induction of the signature cytokines and chemokines of the hyperinflammatory state associated with severe morbidity and mortality in COVID-19. Here a case is made for considering IRAK4 or IRF5 inhibitors as potential therapies for the "cytokine storm" of COVID-19.