Endogenous IL-33 and Its Autoamplification of IL-33/ST2 Pathway Play an Important Role in Asthma

Mechanistic role of RND3-regulated IL33/ST2 signaling on cardiomyocyte senescence

Hyperinflammatory responses are pivotal in the cardiomyocyte senescence pathophysiology, with IL33 serving as a crucial pro-inflammatory mediator. Our previous findings highlighted RND3's suppressive effect on IL33 expression. This study aims to explore the role of RND3 in IL33/ST2 signaling activation and in cardiomyocyte senescence. Intramyocardial injection of exogenous IL33 reduces the ejection fraction and fractional shortening of rats, inducing the appearance of senescence-associated secretory phenotype (SASP) in myocardial tissues. Recombinant IL33 treatment of AC16 cardiomyocytes significantly upregulated expression of SASP factors like IL1α, IL6, and MCP1, and increased the p-p65/p65 ratio and proportions of SA-β-gal and γH2AX-positive cells. NF-κB inhibitor pyrrolidinedithiocarbamate ammonium (PDTC) and ST2 antibody astegolimab treatments mitigated above effects. RND3 gene knockout H9C2 cardiomyocytes using CRISPR/Cas9 technology upregulated IL33, ST2L, IL1α, IL6, and MCP1 levels, decreased sST2 levels, and increased SA-β-gal and γH2AX-positive cells. A highly possibility of binding between RND3 and IL33 proteins was showed by molecular docking and co-immunoprecipitation, and loss of RND3 attenuated ubiquitination mediated degradation of IL33; what's more, a panel of ubiquitination regulatory genes closely related to RND3 were screened using qPCR array. In contrast, RND3 overexpression in rats by injection of AAV9-CMV-RND3 particles inhibited IL33, ST2L, IL1α, IL6, and MCP1 expression in cardiac tissues, decreased serum IL33 levels, and increased sST2 levels. These results suggest that RND3 expression in cardiomyocytes modulates cell senescence by inhibiting the IL33/ST2/NF-κB signaling pathway, underscoring its potential as a therapeutic target in cardiovascular senescence.

Blocking group 2 innate lymphoid cell activation and macrophage M2 polarization: potential therapeutic mechanisms in ovalbumin-induced allergic asthma by calycosin

BACKGROUND

Calycosin, a flavonoid compound extracted from Astragalus membranaceus, has shown anti-asthma benefits in house dust mite-induced asthma. Recent studies have suggested that innate-type cells, including group 2 innate lymphoid cells (ILC2s) and macrophages, serve as incentives for type 2 immunity and targets for drug development in asthma. This work focuses on the effects of calycosin on the dysregulated ILC2s and macrophages in allergic asthma.

METHODS

In vivo, the asthmatic mouse model was established with ovalbumin (OVA) sensitization and challenge, and calycosin was intraperitoneally administered at doses of 20 and 40 mg/kg. In vivo, mouse primary ILC2s were stimulated with interleukin (IL)-33 and mouse RAW264.7 macrophages were stimulated with IL-4 and IL-13 to establish the cell models. Cells were treated with calycosin at doses of 5 and 10 µM.

RESULTS

In vivo, we observed significantly reduced numbers of eosinophils, neutrophils, monocyte macrophages and lymphocytes in the bronchoalveolar lavage fluid (BALF) of OVA-exposed mice with 40 mg/kg calycosin. Histopathological assessment showed that calycosin inhibited the airway inflammation and remodeling caused by OVA. Calycosin markedly decreased the up-regulated IL-4, IL-5, IL-13, IL-33, and suppression tumorigenicity 2 (ST2) induced by OVA in BALF and/or lung tissues of asthmatic mice. Calycosin repressed the augment of arginase 1 (ARG1), IL-10, chitinase-like 3 (YM1) and mannose receptor C-type 1 (MRC1) levels in the lung tissues of asthmatic mice. In vivo, calycosin inhibited the IL-33-induced activation as well as the increase of IL-4, IL-5, IL-13 and ST2 in ILC2s. Calycosin also repressed the increase of ARG1, IL-10, YM1 and MRC1 induced by IL-4 and IL-13 in RAW264.7 macrophages. In addition, we found that these changes were more significant in 40 mg/kg calycosin treatment than 20 mg/kg calycosin.

CONCLUSIONS

Collectively, this study showed that calycosin might attenuate OVA-induced airway inflammation and remodeling in asthmatic mice via preventing ILC2 activation and macrophage M2 polarization. Our study might contribute to further study of asthmatic therapy.

Merging and imputation of flow cytometry data: A critical assessment

Although most modern techniques and analysis methods in multiparameter flow cytometry (MFC) allow for increased dimensionality for the characterization and quantification of cell populations, most MFC applications depend on flow cytometers measuring relatively small (<16) numbers of parameters. When more markers than the available parameters need to be acquired, these are commonly distributed over multiple independent measurements that include a backbone of common markers. Several methods have been proposed to impute values for combinations of markers that were not measured simultaneously. These imputation methods are frequently used without proper validation and knowledge of their effects on data analysis. We evaluated the performance of existing imputation software (Infinicyt, CyTOFmerge, CytoBackBone, and cyCombine) in approximating known measured expression data in terms of similarity in visual appearance, cell expression, and gating in different datasets by splitting MFC samples into separate measurements with partially overlapping markers and re-calculating missing marker expression. Out of the assessed packages, CyTOFmerge showed the most accurate approximation of the known expression in terms of similar expression values and concordance with manual gating, with a mean F-score between 0.53 and 0.87 when retrieving cell populations in different datasets. Performance remained inadequate for all methods, with only limited similarity at the cell level. In conclusion, the use of imputed MFC data should take such limitations into account and include independent validation of results to justify conclusions.

TRAF4 is crucial for ST2+ memory Th2 cell expansion in IL-33-driven airway inflammation

Tumor necrosis factor receptor-associated factor 4 (TRAF4) is an important regulator of type 2 responses in the airway; however, the underlying cellular and molecular mechanisms remain elusive. Herein, we generated T cell-specific TRAF4-deficient (CD4-cre Traf4fl/fl) mice and investigated the role of TRAF4 in memory Th2 cells expressing IL-33 receptor (ST2, suppression of tumorigenicity 2) (ST2+ mTh2 cells) in IL-33-mediated type 2 airway inflammation. We found that in vitro-polarized TRAF4-deficient (CD4-cre Traf4fl/fl) ST2+ mTh2 cells exhibited decreased IL-33-induced proliferation as compared with TRAF4-sufficient (Traf4fl/fl) cells. Moreover, CD4-cre Traf4fl/fl mice showed less ST2+ mTh2 cell proliferation and eosinophilic infiltration in the lungs than Traf4fl/fl mice in the preclinical models of IL-33-mediated type 2 airway inflammation. Mechanistically, we discovered that TRAF4 was required for the activation of AKT/mTOR and ERK1/2 signaling pathways as well as the expression of transcription factor Myc and nutrient transporters (Slc2a1, Slc7a1, and Slc7a5), signature genes involved in T cell growth and proliferation, in ST2+ mTh2 cells stimulated by IL-33. Taken together, the current study reveals a role of TRAF4 in ST2+ mTh2 cells in IL-33-mediated type 2 pulmonary inflammation, opening up avenues for the development of new therapeutic strategies.

ILC2 require cell-intrinsic ST2 signals to promote type 2 immune responses

The initiation of type 2 immune responses at mucosal barriers is regulated by rapidly secreted cytokines called alarmins. The alarmins IL-33, IL-25 and TSLP are mainly secreted by stromal and epithelial cells in tissues and were linked to chronic inflammatory diseases, such as allergic lung inflammation, or to resistance against worm infections. Receptors for alarmins are expressed by a variety of immune cells, including group 2 innate lymphoid cells (ILC2s), an early source of the type 2 cytokines, such as IL-5 and IL-13, which have been linked to atopic diseases and anti-worm immunity as well. However, the precise contribution of the IL-33 receptor signals for ILC2 activation still needs to be completed due to limitations in targeting genes in ILC2. Using the newly established Nmur1 iCre-eGFP mouse model, we obtained specific conditional genetic ablation of the IL-33 receptor subunit ST2 in ILC2s. ST2-deficient ILC2s were unresponsive to IL-33 but not to stimulation with the alarmin IL-25. As a result of defective ST2 signals, ILC2s produced limited amounts of IL-5 and IL-13 and failed to support eosinophil homeostasis. Further, ST2-deficient ILC2s were unable to expand and promote the recruitment of eosinophils during allergic lung inflammation provoked by papain administration. During infection with Nippostrongylus brasiliensis, ILC2-intrinsic ST2 signals were required to mount an effective type 2 immune response against the parasite leading to higher susceptibility against worm infection in conditional knockout mice. Therefore, this study argues for a non-redundant role of cell-intrinsic ST2 signals triggering proper activation of ILC2 for initiation of type 2 immunity.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

Resolution Potential of Necrotic Cell Death Pathways

During tissue damage caused by infection or sterile inflammation, not only damage-associated molecular patterns (DAMPs), but also resolution-associated molecular patterns (RAMPs) can be activated. These dying cell-associated factors stimulate immune cells localized in the tissue environment and induce the production of inflammatory mediators or specialized proresolving mediators (SPMs). Within the current prospect of science, apoptotic cell death is considered the main initiator of resolution. However, more RAMPs are likely to be released during necrotic cell death than during apoptosis, similar to what has been observed for DAMPs. The inflammatory potential of many regulated forms of necrotic cell death modalities, such as pyroptosis, necroptosis, ferroptosis, netosis, and parthanatos, have been widely studied in necroinflammation, but their possible role in resolution is less considered. In this review, we aim to summarize the relationship between necrotic cell death and resolution, as well as present the current available data regarding the involvement of certain forms of regulated necrotic cell death in necroresolution.

Signaling and functions of interleukin-33 in immune regulation and diseases

Interleukin-33 (IL-33) which belongs to the interleukin-1 (IL-1) family is an alarmin cytokine with critical roles in tissue homeostasis, pathogenic infection, inflammation, allergy and type 2 immunity. IL-33 transmits signals through its receptor IL-33R (also called ST2) which is expressed on the surface of T helper 2 (Th2) cells and group 2 innate lymphoid cells (ILC2s), thus inducing transcription of Th2-associated cytokine genes and host defense against pathogens. Moreover, the IL-33/IL-33R axis is also involved in development of multiple types of immune-related diseases. In this review, we focus on current progress on IL-33-trigggered signaling events, the important functions of IL-33/IL-33R axis in health and diseases as well as the promising therapeutic implications of these findings.

Therapeutic Potential of a Combination of Electroacupuncture and Human iPSC-Derived Small Extracellular Vesicles for Ischemic Stroke

This paper aimed to explore the roles of the combination of electroacupuncture (EA) and induced pluripotent stem cell-derived small extracellular vesicles (iPSC-EVs) on mice with ischemic stroke and the underlying mechanisms. A focal cerebral ischemia model was established in C57BL/6 mice through middle cerebral artery occlusion (MCAO). After 3 days, neurological impairment and motor function were examined by performing behavioral tests. The infarct volume and neuronal apoptosis were examined using TTC staining and TUNEL assays. Flow cytometry was performed to assess the proliferation of T lymphocytes. The changes in the interleukin (IL)-33/ST2 axis were evaluated by immunofluorescence and Western blotting. The combination of EA and iPSC-EVs treatment ameliorated neurological impairments and reduced the infarct volume and neuronal apoptosis in MCAO mice. EA plus iPSC-EVs suppressed T helper (Th1) and Th17 responses and promoted the regulatory T cell (Treg) response. In addition, EA plus iPSC-EVs exerted neuroprotective effects by regulating the IL-33/ST2 axis and inhibiting the microglia and astrocyte activation. Taken together, the study shows that EA and iPSC-EVs exerted a synergistic neuroprotective effect in MCAO mice, and this treatment may represent a novel potent therapy for ischemic stroke and damage to other tissues.

Therapeutic Effects of an Anti-sialyl Lewis X Antibody in a Murine Model of Allergic Asthma

Asthma is an allergic disease that causes severe infiltration of leukocytes into the lungs. Leukocyte infiltration is mediated by the binding of sialyl Lewis X (sLex) glycans present on the leukocytes to E-and P-selectins present on the endothelial cells at the sites of inflammation. Here, we found that mouse eosinophils express sLex glycans, and their infiltration into the lungs and proliferation in the bone marrow were significantly suppressed by an anti-sLex monoclonal antibody (mAb) F2 in a murine model of ovalbumin-induced asthma. The percentage of eosinophils in the bronchoalveolar lavage fluid and bone marrow and serum IgE levels decreased significantly in the F2-administered mice. Levels of T helper type 2 (Th2) cytokines and chemokines, involved in IgE class switching and eosinophil proliferation and recruitment, were also decreased in the F2-administered mice. An ex vivo cell rolling assay revealed that sLex glycans mediate the rolling of mouse eosinophils on P-selectin-expressing cells. These results indicate that the mAb F2 exerts therapeutic effects in a murine model of allergen-induced asthma, suggesting that sLex carbohydrate antigen could serve as a novel therapeutic target for allergic asthma.

Early Measurement of Blood sST2 Is a Good Predictor of Death and Poor Outcomes in Patients Admitted for COVID-19 Infection

Although several biomarkers have shown correlation to prognosis in COVID-19 patients, their clinical value is limited because of lack of specificity, suboptimal sensibility or poor dynamic behavior. We hypothesized that circulating soluble ST2 (sST2) could be associated to a worse outcome in COVID-19. In total, 152 patients admitted for confirmed COVID-19 were included in a prospective non-interventional, observational study. Blood samples were drawn at admission, 48-72 h later and at discharge. sST2 concentrations and routine blood laboratory were analyzed. Primary endpoints were admission at intensive care unit (ICU) and mortality. Median age was 57.5 years [Standard Deviation (SD: 12.8)], 60.4% males. 10% of patients (n = 15) were derived to ICU and/or died during admission. Median (IQR) sST2 serum concentration (ng/mL) rose to 53.1 (30.9) at admission, peaked at 48-72 h (79.5(64)) and returned to admission levels at discharge (44.9[36.7]). A concentration of sST2 above 58.9 ng/mL was identified patients progressing to ICU admission or death. Results remained significant after multivariable analysis. The area under the receiver operating characteristics curve (AUC) of sST2 for endpoints was 0.776 (p = 0.001). In patients admitted for COVID-19 infection, early measurement of sST2 was able to identify patients at risk of severe complications or death.

Oxidation-Dependent Activation of Src Kinase Mediates Epithelial IL-33 Production and Signaling during Acute Airway Allergen Challenge

The respiratory epithelium forms the first line of defense against inhaled pathogens and acts as an important source of innate cytokine responses to environmental insults. One critical mediator of these responses is the IL-1 family cytokine IL-33, which is rapidly secreted upon acute epithelial injury as an alarmin and induces type 2 immune responses. Our recent work highlighted the importance of the NADPH oxidase dual oxidase 1 (DUOX1) in acute airway epithelial IL-33 secretion by various airborne allergens associated with H2O2 production and reduction-oxidation-dependent activation of Src kinases and epidermal growth factor receptor (EGFR) signaling. In this study, we show that IL-33 secretion in response to acute airway challenge with house dust mite (HDM) allergen critically depends on the activation of Src by a DUOX1-dependent oxidative mechanism. Intriguingly, HDM-induced epithelial IL-33 secretion was dramatically attenuated by small interfering RNA- or Ab-based approaches to block IL-33 signaling through its receptor IL1RL1 (ST2), indicating that HDM-induced IL-33 secretion includes a positive feed-forward mechanism involving ST2-dependent IL-33 signaling. Moreover, activation of type 2 cytokine responses by direct airway IL-33 administration was associated with ST2-dependent activation of DUOX1-mediated H2O2 production and reduction-oxidation-based activation of Src and EGFR and was attenuated in Duox1 -/- and Src +/- mice, indicating that IL-33-induced epithelial signaling and subsequent airway responses involve DUOX1/Src-dependent pathways. Collectively, our findings suggest an intricate relationship between DUOX1, Src, and IL-33 signaling in the activation of innate type 2 immune responses to allergens, involving DUOX1-dependent epithelial Src/EGFR activation in initial IL-33 secretion and in subsequent IL-33 signaling through ST2 activation.

Molecular hydrogen alleviates asthma through inhibiting IL-33/ILC2 axis

BACKGROUND

Asthma is one of the most common noninfectious chronic diseases characterized by type II inflammation. This study aimed to investigate the effects of molecular hydrogen on the pathogenesis of asthma.

METHODS

OVA sensitized asthma mouse model and house dust mite treated 16HBE cellular model were established and hydrogen/oxygen mixture was used to treat asthmatic mice and 16HBE cells. Serum and BALF cytokines were measured with specific ELISA assays. E-cadherin and ZO-1 were detected by immunohistochemical staining and expression of caspase 3 and 9, NF-κB, IL-33 and ST2 was assessed by quantitative real-time PCR, western blot and/or immunofluorescence. IL-33 promoter activity was analyzed by dual-luciferase assay. ILC2 population was assayed by flow cytometry and differentially expressed miRNAs were detected using miRNA array.

RESULTS

Serum and BALF levels of IL-33 and other alarmin and type II cytokines were greatly increased by OVA and inhibited by H2 in asthmatic mice. The expression of NF-κB (p65) and ST2 was upregulated by OVA and suppressed by H2. ILC2 population was markedly increased in OVA-induced asthmatic mice, and such increase was inhibited by H2. E-cadherin and ZO-1 levels in airway tissues of asthmatic mice were significantly lower than that of control mice, and the reduction was recovered by H2 treatment. H2 alleviated HDM induced apoptosis of 16HBE cells, upregulation of IL-33 and ST2, and elevation of IL-33 promoter activity. A group of miRNAs differentially expressed in HDM and HDM + H2 treated 16HBE cells were identified.

CONCLUSIONS

These data demonstrated that H2 is efficient in suppressing allergen-induced asthma and could be developed as a therapeutics for asthma and other conditions of type II inflammation.

Screening Cancer Immunotherapy: When Engineering Approaches Meet Artificial Intelligence

Immunotherapy is a class of promising anticancer treatments that has recently gained attention due to surging numbers of FDA approvals and extensive preclinical studies demonstrating efficacy. Nevertheless, further clinical implementation has been limited by high variability in patient response to different immunotherapeutic agents. These treatments currently do not have reliable predictors of efficacy and may lead to side effects. The future development of additional immunotherapy options and the prediction of patient-specific response to treatment require advanced screening platforms associated with accurate and rapid data interpretation. Advanced engineering approaches ranging from sequencing and gene editing, to tumor organoids engineering, bioprinted tissues, and organs-on-a-chip systems facilitate the screening of cancer immunotherapies by recreating the intrinsic and extrinsic features of a tumor and its microenvironment. High-throughput platform development and progress in artificial intelligence can also improve the efficiency and accuracy of screening methods. Here, these engineering approaches in screening cancer immunotherapies are highlighted, and a discussion of the future perspectives and challenges associated with these emerging fields to further advance the clinical use of state-of-the-art cancer immunotherapies are provided.

What Makes the Lung Unique – Tissue-Specific Immunity in the Respiratory Tract

The immune system constitutes a critical mechanism of the human body to preserve health and mitigate disease. In the lung, immunity is seen as a critical driver in many respiratory diseases, in particular in those characterised by aberrant inflammation, such as chronic obstructive pulmonary disease, fibrosis, and asthma. In this review, the specialised set of immune cells and lung tissue-specific regulators, including key cytokines such as granulocyte-macrophage colony-stimulating factor and transforming growth factor β, that control immune responses in the respiratory tract will be discussed. Furthermore, the current understanding of the impact of key environmental components such as the role of oxygen and lung microbiota on lung immunity will be highlighted. The goal is to identify the unique aspects of lung immune biology to facilitate insights into the aetiology of common lung inflammatory diseases and to provide the basis for a deeper mechanistic understanding of the underlying immune processes. Finally, key future avenues of research such as using more comprehensive quantitative approaches for elucidating molecular disease mechanisms as well as the potential to exploit tissue-specific regulators of immunity for therapy of lung inflammatory disorders will be discussed.

Contributions of IL-33 in Non-hematopoietic Lung Cells to Obstructive Lung Disease

Interleukin (IL)-33 plays important roles in pulmonary immune responses and lung diseases including asthma and chronic obstructive pulmonary disease (COPD). There is substantial interest in identifying and characterizing cellular sources vs. targets of IL-33, and downstream signaling pathways involved in disease pathophysiology. While epithelial and immune cells have largely been the focus, in this review, we summarize current knowledge of expression, induction, and function of IL-33 and its receptor ST2 in non-hematopoietic lung cells in the context of health and disease. Under basal conditions, epithelial cells and endothelial cells are thought to be the primary resident cell types that express high levels of IL-33 and serve as ligand sources compared to mesenchymal cells (smooth muscle cells and fibroblasts). Under inflammatory conditions, IL-33 expression is increased in most non-hematopoietic lung cells, including epithelial, endothelial, and mesenchymal cells. In comparison to its ligand, the receptor ST2 shows low expression levels at baseline but similar to IL-33, ST2 expression is upregulated by inflammation in these non-hematopoietic lung cells which may then participate in chronic inflammation both as sources and autocrine/paracrine targets of IL-33. Downstream effects of IL-33 may occur via direct receptor activation or indirect interactions with the immune system, overall contributing to lung inflammation, airway hyper-responsiveness and remodeling (proliferation and fibrosis). Accordingly from a therapeutic perspective, targeting IL-33 and/or its receptor in non-hematopoietic lung cells becomes relevant.