IL-33 in autoimmunity; possible therapeutic target

Edwardsiella tarda induces airways inflammation and production of autoantibodies against lung tissues through regulation of the IL-33-ST2 axis

Chronic obstructive pulmonary disease (COPD) is a highly prevalent chronic respiratory disease characterised by irreversible airways obstruction associated with chronic airways inflammation and remodelling, while the pathogenesis and the mechanistic differences between patients remain to be fully elucidated. We previously reported that alarmin cytokine IL-33 may contribute to the production of autoantibodies against respiratory epithelial cells. Here we expand the hypothesis that pulmonary autoimmune responses induced by airway microbiota also contribute to the progression of COPD. We focused on Edwardsiella tarda which we detected uniquely in the induced sputum of patients with acute exacerbations of COPD. Pernasal challenge of the airways of WT mice with supernatants of cultured E. tarda induced marked, elevated expression of IL-33 in the lung tissues. Immunisation of animals with supernatants of cultured E. tarda resulted in significantly elevated airways inflammation, the formation of tertiary lymphatic structures and significantly elevated proportions of T follicular helper T cells in the lung tissue and mediastinal lymph nodes. Interestingly, such challenge also induced production of IgG autoantibodies directed against lung tissue lysate, alveolar epithelial cell proteins and elastin fragment, while putrescine, one of metabolites generated by the bacterium, might play an important role in the autoantibody production. Furthermore, all of these effects were partly but significantly abrogated in mice with deletion of the IL-33 receptor ST2. Collectively, these data support the hypothesis that COPD is progressed at least partly by airways microbiota such as E. tarda initiating autoimmune attack of the airways epithelium mediated at least partly through the IL-33-ST2 axis.

IL-33 in Ischemic Stroke: Brain vs. Periphery

Cerebrovascular disease is the second-leading cause of death and disability worldwide, with stroke being the most common cause. In ischemic stroke, several processes combine to produce immunosuppression, leaving the post-stroke body susceptible to infection, which in turn affects neuroinflammation. Interleukin-33 (IL-33), a member of the interleukin-1 family (IL-1), functions as a modulator of immune responses and inflammation, playing a crucial role in the establishment of immunologic responses. IL-33 has been shown to have a protective effect on brain injury and represents a potential target by modulating inflammatory cytokines and stimulating immune regulatory cells. With an emphasis on preclinical and clinical studies, this review covers the impact of IL-33 on immune system mechanisms following ischemic stroke.

Interleukin-33/serum stimulation-2 pathway: Regulatory mechanisms and emerging implications in immune and inflammatory diseases

Interleukin (IL)- 33, a nuclear factor and pleiotropic cytokine of the IL-1 family, is gaining attention owing to its important role in chronic inflammatory and autoimmune diseases. This review extends our knowledge of the effects exerted by IL-33 on target cells by binding to its specific receptor serum stimulation-2 (ST2). Depending on the tissue context, IL-33 performs multiple functions encompassing host defence, immune response, initiation and amplification of inflammation, tissue repair, and homeostasis. The levels and activity of IL-33 in the body are controlled by complex IL-33-targeting regulatory pathways. The unique temporal and spatial expression patterns of IL-33 are associated with host homeostasis and the development of immune and inflammatory disorders. Therefore, understanding the origin, function, and processes of IL-33 under various conditions is crucial. This review summarises the regulatory mechanisms underlying the IL-33/ST2 signalling axis and its potential role and clinical significance in immune and inflammatory diseases, and discusses the current complex and conflicting findings related to IL-33 in host responses.

Spatial Transcriptomics Resolve an Emphysema-Specific Lymphoid Follicle B Cell Signature in Chronic Obstructive Pulmonary Disease

Rationale: Within chronic obstructive pulmonary disease (COPD), emphysema is characterized by a significant yet partially understood B cell immune component. Objectives: To characterize the transcriptomic signatures from lymphoid follicles (LFs) in ever-smokers without COPD and patients with COPD with varying degrees of emphysema. Methods: Lung sections from 40 patients with COPD and ever-smokers were used for LF proteomic and transcriptomic spatial profiling. Formalin- and O.C.T.-fixed lung samples obtained from biopsies or lung explants were assessed for LF presence. Emphysema measurements were obtained from clinical chest computed tomographic scans. High-confidence transcriptional target intersection analyses were conducted to resolve emphysema-induced transcriptional networks. Measurements and Main Results: Overall, 115 LFs from ever-smokers and Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1-2 and GOLD 3-4 patients were analyzed. No LFs were found in never-smokers. Differential gene expression analysis revealed significantly increased expression of LF assembly and B cell marker genes in subjects with severe emphysema. High-confidence transcriptional analysis revealed activation of an abnormal B cell activity signature in LFs (q-value = 2.56E-111). LFs from patients with GOLD 1-2 COPD with emphysema showed significantly increased expression of genes associated with antigen presentation, inflammation, and B cell activation and proliferation. LFs from patients with GOLD 1-2 COPD without emphysema showed an antiinflammatory profile. The extent of centrilobular emphysema was significantly associated with genes involved in B cell maturation and antibody production. Protein-RNA network analysis showed that LFs in emphysema have a unique signature skewed toward chronic B cell activation. Conclusions: An off-targeted B cell activation within LFs is associated with autoimmune-mediated emphysema pathogenesis.

Potential mechanistic roles of Interleukin-33 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that occurs mainly in synovial joints, causing synovial inflammation and joint injury. If diagnosed and treated in time, the disease can be well controlled. However, in clinical practice, patients often fail to get timely and effective treatment due to misdiagnosis, missed diagnosis, and other reasons, resulting in deterioration of the condition and poor prognosis, seriously affecting the patient's quality of life. So far, the pathogenesis of RA is still unclear. In recent years, it has been found that the imbalance of cytokines plays a vital role in the occurrence and development of RA. Most RA-related cytokines are produced by immune cells, which bind to the specific receptors of effector cells through paracrine and autocrine pathways. The effect of cytokines on inflammation can be divided into pro-inflammatory and anti-inflammatory factors. When the impact of pro-inflammatory factors is more significant than anti-inflammatory factors, the condition of RA will be aggravated, resulting in more inflammatory severe reactions and immune disorders. Interleukin-33 (IL-33) is a new member of the interleukin-1(IL-1) family, and its receptor is suppression of tumorigenicity 2 (ST2). IL-33 plays a vital role in immune diseases such as RA by promoting a series of biochemical reactions in macrophages, mast cells, granulocytes, and other cells. This article aims to summarize the research progress of IL-33 in the pathogenesis of RA in recent years, discuss its role in the pathogenesis of RA, and provide new ideas for the prevention and treatment of RA in the future.

Identification and exploration of pharmacological pyroptosis-related biomarkers of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD). Its etiology is unclear. Much evidence suggests that the death of abnormal intestinal epithelial cells (IECs) leads to intestinal barrier disruption, and the subsequent inflammatory response plays a vital role in UC. Pyroptosis is a form of programmed inflammatory cell death, and the role of pyroptosis in UC etiology remains to be explored. This study identified 10 hub genes in pyroptosis by gene expression profiles obtained from the GSE87466 dataset. Meanwhile, the biomarkers were screened based on gene significance (GS) and module membership (MM) through the Weighted Gene Co-Expression Network Analysis (WGCNA). The following analysis indicated that hub genes were closely associated with the UC progression and therapeutic drug response. The single-cell RNA (scRNA) sequencing data from UC patients within the GSE162335 dataset indicated that macrophages were most related to pyroptosis. Finally, the expression of hub genes and response to the therapeutic drug [5-aminosalicylic acid (5-ASA)] were verified in dextran sulfate sodium (DSS)-induced colitis mice. Our study identified IL1B as the critical pyroptosis-related biomarker in UC. The crosstalk between macrophage pyroptosis and IEC pyroptosis may play an essential role in UC, deserving further exploration.