Evaluation of new and old biomarkers in dogs with degenerative mitral valve disease

Background

Dogs with degenerative mitral valve disease are commonly presented to small animal clinicians. Diagnosis, clinical staging, and therapeutic design are based on a combination of clinical examination, radiography, and echocardiography. To support diagnosis and clinical monitoring, a multi-marker-based approach would be conceivable. The aim of this study was to investigate the suitability of Galectin-3 and interleukin-1 receptor-like 1 protein (ST2) in dogs with degenerative mitral valve disease in accordance with N-terminal-prohormone-B-type natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI). For this purpose, serum concentrations of Galectin-3 and ST2 of 64 dogs with different stages of mitral valve disease and 21 dogs without cardiac disease were analyzed at the first examination and six months later. Echocardiography, blood cell count and clinical chemistry were performed and established biomarkers NT-proBNP and cTnI were measured additionally. Differences in the biomarker concentrations between all groups at both timepoints and the change in biomarker concentrations from first to second evaluation was investigated. Furthermore, correlations of each biomarker, between biomarkers and echocardiographic measurements, were calculated. Finally, the receiver-operating characteristic curve and the area under the curve analysis were performed to differentiate between disease stages and controls.

Results

Serum concentrations of Galectin-3 and ST2 were not statistically different between canine patients in the respective stages of mitral valve disease or in comparison to dogs in the control group at any timepoint. A significant increase in ST2 concentrations from the baseline to the follow-up examination was observed in dogs classified as stage B1 and the control group. The concentrations of NT-proBNP and cTnI in stage C dogs were significantly increased in comparison to the other groups.

Conclusions

In this study, no relation between Galectin-3 and ST2 levels to the presence or stage of mitral valve disease could be detected. Nevertheless, considering the increase in ST2 concentrations from the first to second measurement, its value on monitoring disease progress could be feasible. In agreement with previous studies, NT-proBNP and cTnI have once more proven their utility in assessing disease severity. The approach of examining new cardiac biomarkers in dogs is still worth pursuing.

Elevated Plasma Soluble ST2 Levels are Associated With Neuronal Injury and Neurocognitive Impairment in Children With Cerebral Malaria

Background

Murine experimental cerebral malaria studies suggest both protective and deleterious central nervous system effects from alterations in the interleukin-33 (IL-33)/ST2 pathway.

Methods

We assessed whether soluble ST2 (sST2) was associated with neuronal injury or cognitive impairment in a cohort of Ugandan children with cerebral malaria (CM, n=224) or severe malarial anemia (SMA, n=193).

Results

Plasma concentrations of sST2 were higher in children with CM than in children with SMA or in asymptomatic community children. Cerebrospinal fluid (CSF) sST2 levels were elevated in children with CM compared with North American children. Elevated plasma and CSF ST2 levels in children with CM correlated with increased endothelial activation and increased plasma and CSF levels of tau, a marker of neuronal injury. In children with CM who were ≥5 years of age at the time of their malaria episode, but not in children <5 years of age, elevated risk factor-adjusted plasma levels of sST2 were associated with worse scores for overall cognitive ability and attention over a 2-year follow-up.

Conclusions

The study findings suggest that sST2 may contribute to neuronal injury and long-term neurocognitive impairment in older children with CM.

Association of ST2 Elevation in the Early Third Trimester with Heart Failure and Pre-Eclampsia in the Peripartum Period

Background: Although high-risk pregnancies are common in clinical practice, there are limited data on the association of soluble suppression of tumorigenicity 2 (ST2) with pregnancy-related complications. The rates of maternal complications, including heart failure (HF) during the peripartum period, were evaluated according to the ST2 level. Methods: A single-center retrospective cohort study included and stratified 259 women with high-risk pregnancies in their early third trimester according to the ST2 levels. The primary endpoint was the occurrence of peripartum HF based on symptoms, N-terminal pro-brain natriuretic peptide, or echocardiography associated with fluid retention. The secondary endpoints consisted of pre-eclampsia, silent pleural effusion, and pericardial effusion during the peripartum period. We performed a logistic model for the association between ST2 and maternal complications. Results: Of the 259 patients (mean age: 36.4 years, mean gestational duration: 31.6 weeks), advanced age ≥35 years and twin gestation were the most prevalent risk factors. Patients with ST2 ≥ 35 ng/mL showed enlarged cardiac chambers. Peripartum HF occurred in 2 (1.6%) out of 121 patients with ST2 < 35 ng/mL and in 47 (34%) out of 138 patients with ST2 ≥ 35 ng/mL. Those with ST2 ≥ 35 ng/mL were more likely to have the secondary endpoints (40.6% vs. 5.8%, p < 0.001). After adjustment, ST2 ≥ 35 ng/mL was associated with a six-fold occurrence of peripartum HF and a four-fold increase in the secondary endpoints. Conclusions: In women with high-risk pregnancies, peripartum HF and pre-eclampsia were not uncommon, and ST2 ≥ 35 ng/mL in the third trimester was independently related to maternal complications.

Changes in Cardiac Biomarkers in Association with Alterations in Cardiac Structure and Function, and Health Status in HFrEF: The EVALUATE-HF Trial

AIMS

N-terminal pro-B-type natriuretic peptide (NT-proBNP), cardiac troponin T (cTnT) and soluble ST2 (sST2) provide complementary prognostic information in HF with reduced ejection fraction (HFrEF). We aimed to assess the association between changes in these markers with changes in cardiac structure, function and health status.

METHODS AND RESULTS

Patients in the EVALUATE-HF trial (N=464) were randomized to sacubitril/valsartan or enalapril for 12 weeks, followed by 12-week open-label sacubitril/valsartan. Cardiac biomarkers, echocardiography, and Kansas City Cardiomyopathy Questionnaires (KCCQ) were completed at baseline, and after 12 and 24 weeks. A total of 410 patients (88%) had serial biomarker measurements available (mean age 67±9 years, 75% male and 75% white). After 24 weeks of treatment NT-proBNP, sST2 and cTnT decreased by median (Q1,Q3) -31% (-55%,+6%), -6% (-19%,+8%) and -3% (-13%,+8%), respectively (all P<0.001). Decreases in NT-proBNP were associated with reductions in cardiac volumes and improvements in systolic and diastolic function and health status. Decreases in cTnT were associated with reductions in LV mass, but not with changes in LV function or KCCQ. Decreases in sST2 were consistently associated with improvements in health status, but not with measures of cardiac structure or function. There were no effect modification from treatment on the associations investigated (P-for-interaction>0.05).

CONCLUSION

In HFrEF, serial changes in NT-proBNP correlate with changes in several key measures of cardiac structure and health status. cTnT changes correlate with changes in LV mass and sST2 with changes in health status. These data highlight possible complementary pathophysiologic implications of changes NT-proBNP, cTnT and sST2.

IL-33/ST2 Axis Protects Against Traumatic Brain Injury Through Enhancing the Function of Regulatory T Cells

Traumatic brain injury (TBI) is a devastating condition due to its long-term sequelae on neurological functions. Inflammatory responses after TBI are critical for injury expansion and repair. Recent research in central nervous system (CNS) disorders reveals the importance of IL-33 and its receptor (ST2) as an alarmin system to initiate immune responses. This study explored the role of IL-33/ST2 signaling in TBI. TBI was induced in adult male C57BL/6J mice using a controlled cortical impact (CCI) model. We found that the expression of IL-33 increased in the injured brain and blood, and ST2 was elevated in the circulating and infiltrating regulatory T cells (Tregs) early after TBI. ST2 deficient mice exhibited reduced Treg numbers in the blood and brain 5 days after TBI. The brain lesion size was enlarged in ST2 knockout mice, which was accompanied by deteriorated sensorimotor function 5 days after TBI. In contrast, post-TBI treatment with IL-33 (2 μg/30 g body weight, intranasal) for 3 days significantly reduced brain lesion size and improved neurological functions 5 days after TBI. Meanwhile, IL-33 treatment increased ST2 expression in circulating and brain infiltrating Tregs. To further explore the involvement of Tregs in IL-33/ST2-mediated neuroprotection, Tregs were depleted by CD25 antibody injection. The absence of Tregs significantly reduced the protective effect of IL-33 after TBI. In vitro study confirmed that IL-33 (50 ng/ml) increased the production of IL-10 and TGFβ from activated Tregs and boosted the inhibitory effect of Tregs on T effector cell proliferation. Taken together, this study suggests that the activation of IL-33/ST2 signaling reduces brain lesion size and alleviates functional deficits after TBI at least partially through regulating the Treg response. IL-33 may represent a new immune therapeutic strategy to improve TBI outcomes.

Diastolic stress echocardiography and biomarkers in patients with preserved left ventricle ejection fraction and heart failure symptoms

INTRODUCTION

Diastolic dysfunction (DD) is a diagnostic challenge in clinical practice.

AIM

The aim of our study was to evaluate the value of diastolic stress echocardiography (DSE) and heart failure (HF) biomarkers in patients with preserved left ventricle ejection fraction (LVEF) and HF symptoms.

METHODS

All the consecutive patients with HF symptoms, preserved LVEF and suspected DD were examined in transthoracic echocardiography (TTE) and DSE using the protocol according to the ASE recommendations. Moreover, blood samples were taken 30 minutes before and after DSE for the following lab markers: N-terminal pro-B type natriuretic peptide (NT-proBNP), mid regional pro atrial natriuretic peptide (MR-proANP) and serum soluble ST2 receptor (ST2).

RESULTS

The study group included 80 patients (mean [standard deviation, SD] age, 69 (8.1) years; 25% males) with dyspnea (New York Heart Association scale IIa - 53; IIb - 17; III - 10) and risk factors: hypertension (96%), diabetes (41%), obesity (56%) and known coronary artery disease (10%). The rest transthoracic echocardiographic (TTE) showed preserved systolic function (mean [SD], LVEF 61.1 [10.5]%) and normal or indeterminate diastolic function. DSE revealed positive result for diastolic dysfunction in 17 patients (21%). The receiver operating characteristic (ROC) analysis showed that age (the area under the curve [AUC], 0.725; P <0.01), left atrial volume indexed for body surface area [LAVI] rest (AUC, 0.722; P <0.01), E/e' rest (AUC, 0.790; P <0.01) and baseline NT-proBNP (AUC, 0.713; P <0.01) predicted positive DSE. Other parameters, including body mass index, baseline E/A, DT or e' were not predictive for DSE result.

CONCLUSIONS

DSE revealed diastolic dysfunction in 21% of study patients and improved the diagnostic value of echocardiography. Rest NT-proBNP, but not MR-proANP and ST2, provided a diagnostic value towards diastolic dysfunction.

The Osteocyte Stimulated by Wnt Agonist SKL2001 Is a Safe Osteogenic Niche Improving Bioactivities in a Polycaprolactone and Cell Integrated 3D Module

Finding and constructing an osteogenic microenvironment similar to natural bone tissue has always been a frontier topic in orthopedics. We found that osteocytes are targeting cells controlling bone anabolism produced by PTH (JBMR 2017, PMID: 27704638), and osteocytes with activated Wnt signaling orchestrate bone formation and resorption (PNAS 2015, PMID: 25605937). However, methods for taking advantage of the leading role of osteocytes in bone regeneration remain unexplored. Herein, we found that the osteocytes with SKL2001-activated Wnt signaling could be an osteogenic microenvironment (SOOME) which upregulates the expression of bone transcription factor Runx2 and Bglap and promotes the differentiation of bone marrow stromal cell ST2 into osteoblasts. Interestingly, 60 μM SKL2001 treatment of osteocytic MLO-Y4 for 24 h maintained Wnt signaling activation for three days after removal, which was sufficient to induce osteoblast differentiation. Triptonide, a Wnt inhibitor, could eliminate this differentiation. Moreover, on day 5, the Wnt signaling naturally decreased to the level of the control group, indicating that this method of Wnt-signaling induction is safe to use. We quickly verified in vivo function of SOOME to a good proximation in 3D bioprinted modules composed of reciprocally printed polycaprolactone bundles (for support) and cell bundles (for bioactivity). In the cell bundles, SOOME stably supported the growth and development of ST2 cells, the 7-day survival rate was as high as 91.6%, and proliferation ability increased linearly. Similarly, SOOME greatly promoted ST2 differentiation and mineralization for 28 days. In addition, SOOME upregulated the expression of angiopoietin 1, promoted endothelial cell migration and angiogenesis, and increased node number and total length of tubes and branches. Finally, we found that the function of SOOME could be realized through the paracrine pathway. This study reveals that osteocytes with Wnt signaling activated by SKL2001 are a safe osteogenic microenvironment. Both SOOME itself and its cell-free culture supernatant can improve bioactivity for osteoblast differentiation, with composite scaffolds especially bearing application value.

IL-33 Promotes ST2-Dependent Fibroblast Maturation via P38 and TGF-β in a Mouse Model of Epidural Fibrosis

BACKGROUND

Recent evidence suggests that IL-33, a novel member of the IL-1β family, is involved in organ fibrosis. However, the roles of IL-33 and its receptor ST2 in epidural fibrosis post spine operation remain elusive.

METHODS

A mouse model of epidural fibrosis was established after laminectomy. IL-33 in the wound tissues post laminectomy was measured with Western blotting, ELISA and immunoflurosence imaging. The fibroblast cell line NIH-3T3 and primary fibroblasts were treated with IL-33 and the mechanisms of maturation of fibroblasts into myofibroblasts were analyzed. To explore roles of IL-33 and its receptor ST2 in vivo, IL-33 knockout (KO) and ST2 KO mice were employed to construct the model of laminectomy. The epidural fibrosis was evaluated using H&E and Masson staining, western-blotting, ELISA and immunohistochemistry.

RESULTS

As demonstrated in western blotting and ELISA, IL-33 was increased in epidural wound tissues post laminectomy. The immunoflurosence imaging revealed that endothelial cells (CD31⁺) and fibroblasts (α-SAM⁺) were major producers of IL-33 in the epidural wound tissues. In vitro, IL-33 promoted fibroblast maturation, which was blocked by ST2 neutralization antibody, suggesting that IL-33-promoted-fibroblasts maturation was ST2 dependent. Further, IL-33/ST2 activated MAPK p38 and TGF-β pathways. Either p38 inhibitor or TGF-β inhibitor decreased fibronectin and α-SAM production from IL-33-treated fibroblasts, suggesting that p38 and TGF-β were involved with IL-33/ST2 signal pathways in the fibroblasts maturation. In vivo, IL-33 KO or ST2 KO decreased fibronectin, α-SMA and collagen deposition in the wound tissues of mice that underwent spine surgery. In addition, TGF-β1 was decreased in IL-33 KO or ST2 KO epidural wound tissues.

CONCLUSION

In summary, IL-33/ST2 promoted fibroblast differentiation into myofibroblasts via MAPK p38 and TGF-β in a mouse model of epidural fibrosis after laminectomy.

Interleukin-33/ Suppression of Tumorigenicity 2 in Renal Fibrosis: Emerging Roles in Prognosis and Treatment

Chronic kidney disease (CKD) is a major public health problem that affects more than 10% of the population worldwide and has a high mortality rate. Therefore, it is necessary to identify novel treatment strategies for CKD. Incidentally, renal fibrosis plays a central role in the progression of CKD to end-stage renal disease (ESRD). The activation of inflammatory pathways leads to the development of renal fibrosis. In fact, interleukin-33 (IL-33), a newly discovered member of the interleukin 1 (IL-1) cytokine family, is a crucial regulator of the inflammatory process. It exerts pro-inflammatory and pro-fibrotic effects via the suppression of tumorigenicity 2 (ST2) receptor, which, in turn, activates other inflammatory pathways. Although the role of this pathway in cardiac, pulmonary, and hepatic fibrotic diseases has been extensively studied, its precise role in renal fibrosis has not yet been completely elucidated. Recent studies have shown that a sustained activation of IL-33/ST2 pathway promotes the development of renal fibrosis. However, with prolonged research in this field, it is expected that the IL-33/ST2 pathway will be used as a diagnostic and prognostic tool for renal diseases. In addition, the IL-33/ST2 pathway seems to be a new target for the future treatment of CKD. Here, we review the mechanisms and potential applications of the IL-33/ST2 pathway in renal fibrosis; such that it can help clinicians and researchers to explore effective treatment options and develop novel medicines for CKD patients.

A Single Administration of Riluzole Applied Acutely After Spinal Cord Injury Attenuates Pro-inflammatory Activity and Improves Long-Term Functional Recovery in Rats

After spinal cord injury (SCI), emergency treatment intervention can minimize tissue damage, which is closely related to the recovery of long-term function. Here, we examined whether the administration of a single dose of riluzole (6 mg/kg) immediately after SCI was a critical window for the drug to exert its regulatory effect and limit long-term neurological deficits. The animals were sacrificed 1 day after administration for investigation of neuronal survival and a potential neuroinflammatory response, and sacrificed in the 6th week for assessment of neurological function. Riluzole applied in a single dose immediately post-SCI decreased the mRNA level of interleukin-1β at 6 h, reduced the destruction of neurons, and reduced the activation of microglia/macrophage M1 expression at day 1 post-SCI. Additionally, riluzole-treated rats showed higher expressions of interleukin-33 and its receptor ST2 in microglia/macrophages of the spinal cord than vehicle-treated rats, suggesting that this signaling pathway might be involved in microglia/macrophage-mediated inflammation. At 6 weeks, riluzole-treated rats exhibited higher motor function scores than vehicle-treated controls. In addition, riluzole-treated rats exhibited higher expression of GAP43 protein and shorter N1 peak latency and larger N1-P1 amplitude in motor-evoked potentials, compared to vehicle-treated rats. Together, these data suggested that early application of riluzole after SCI could be crucial for long-term functional recovery, so it may represent a promising therapeutic candidate within the critical therapeutic window for acute SCI.

Development of an ultra-sensitive human IL-33 biomarker assay for age-related macular degeneration and asthma drug development

Background

Over the past decade, human Interleukin 33 (hIL-33) has emerged as a key contributor to the pathogenesis of numerous inflammatory diseases. Despite the existence of several commercial hIL-33 assays spanning multiple platform technologies, their ability to provide accurate hIL-33 concentration measurements and to differentiate between active (reduced) and inactive (oxidized) hIL-33 in various matrices remains uncertain. This is especially true for lower sample volumes, matrices with low hIL-33 concentrations, and matrices with elevated levels of soluble Interleukin 1 Receptor-Like 1 (sST2), an inactive form of ST2 that competes with membrane bound ST2 for hIL-33 binding.

Results

We tested the performance of several commercially available hIL-33 detection assays in various human matrices and found that most of these assays lacked the sensitivity to accurately detect reduced hIL-33 at biologically relevant levels (sub-to-low pg/mL), especially in the presence of human sST2 (hsST2), and/or lacked sufficient target specificity. To address this, we developed and validated a sensitive and specific enzyme-linked immunosorbent assay (ELISA) capable of detecting reduced and total hIL-33 levels even in the presence of high concentrations of sST2. By incorporating the immuno-polymerase chain reaction (iPCR) platform, we further increased the sensitivity of this assay for the reduced form of hIL-33 by ~ 52-fold. Using this hIL-33 iPCR assay, we detected hIL-33 in postmortem human vitreous humor (VH) samples from donors with age-related macular degeneration (AMD) and found significantly increased hIL-33 levels when compared to control individuals. No statistically significant difference was observed in aqueous humor (AH) from AMD donors nor in plasma and nasosorption fluid (NF) from asthma patients compared to control individuals.

Conclusions

Unlike existing commercial hIL-33 assays, our hIL-33 bioassays are highly sensitive and specific and can accurately quantify hIL-33 in various human clinical matrices, including those with high levels of hsST2. Our results provide a proof of concept of the utility of these assays in clinical trials targeting the hIL-33/hST2 pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03189-3.

The Paradigm Change of IL-33 in Vascular Biology

In this review, we focus on the actual understanding of the role of IL-33 in vascular biology in the context of the historical development since the description of IL-33 as a member of IL-1 superfamily and the ligand for ST2 receptor in 2005. We summarize recent data on the biology, structure and signaling of this dual-function factor with both nuclear and extracellular cytokine properties. We describe cellular sources of IL-33, particularly within vascular wall, changes in its expression in different cardio-vascular conditions and mechanisms of IL-33 release. Additionally, we summarize the regulators of IL-33 expression as well as the effects of IL-33 itself in cells of the vasculature and in monocytes/macrophages in vitro combined with the consequences of IL-33 modulation in models of vascular diseases in vivo. Described in murine atherosclerosis models as well as in macrophages as an atheroprotective cytokine, extracellular IL-33 induces proinflammatory, prothrombotic and proangiogenic activation of human endothelial cells, which are processes known to be involved in the development and progression of atherosclerosis. We, therefore, discuss that IL-33 can possess both protective and harmful effects in experimental models of vascular pathologies depending on experimental conditions, type and dose of administration or method of modulation.

The Effects of Vitamin D on the Expression of IL-33 and Its Receptor ST2 in Skin Cells; Potential Implication for Psoriasis

Interleukin 33 (IL-33) belongs to the IL-1 family and is produced constitutively by epithelial and endothelial cells of various organs, such as the skin. It takes part in the maintenance of tissue homeostasis, repair, and immune response, including activation of Th2 lymphocytes. Its involvement in pathogenesis of several inflammatory diseases including psoriasis was also suggested, but this is not fully understood. The aim of the study was to investigate expression of IL-33 and its receptor, ST2, in psoriasis, and the effects of the active form of vitamin D (1,25(OH)₂D₃) on their expression in skin cells. Here we examined mRNA and protein profiles of IL-33 and ST2 in 18 psoriatic patients and healthy volunteers by qPCR and immunostaining techniques. Potential effects of 1,25(OH)₂D₃ and its receptor (VDR) on the expression of IL-33 and ST2 were tested in cultured keratinocytes, melanocytes, fibroblasts, and basal cell carcinoma cells. It was shown that 1,25(OH)₂D₃ effectively stimulated expression of IL-33 and its receptor ST2’s mRNAs in a time-dependent manner, in keratinocytes and to the lesser extends in melanocytes, but not in fibroblasts. Furthermore, the effect of vitamin D on expression of IL-33 and ST2 was VDR-dependent. Finally, we demonstrated that the expression of mRNA for IL-33 was mainly elevated in the psoriatic skin but not in its margin. Interestingly, ST2 mRNA was downregulated in psoriatic lesion compared to both marginal tissue as well as healthy skin. Our data indicated that vitamin D can modulate IL-33 signaling, opening up new perspectives for our understanding of the mechanism of vitamin D action in psoriasis therapy.

IL-33/ST2 Axis Deficiency Exacerbates Hepatic Pathology by Regulating Treg and Th17 Cells in Murine Schistosomiasis Japonica

Purpose

Schistosoma japonicum-infected IL-33 and ST2 gene deficiency (IL-33^−/− and ST2^−/−, respectively) mice were used to explore the role of the IL-33/ST2 axis in liver pathology targeting regulatory T cells (Treg)/T helper 17 cells (Th17).

Materials and Methods

Each mouse was infected percutaneously with 20 S. japonicum cercariae. Hepatic mass index (HMI), liver egg granulomas, hepatic fibrosis biomarkers and serum levels of alanine aminotransferase (ALT) were investigated. Treg and Th17 frequency was determined by flow cytometry. Expressions of Foxp3, ST2, TGF-β1, IL-10, RORγt, and IL-17A were measured via quantitative real-time polymerase chain reaction (qRT-PCR). Concentrations of TGF-β1, IL-10 and IL-17A were tested with ELISA. In vitro experiments, mRNA expressions of Foxp3, TGF-β1, IL-10, Atg5, Beclin-1 and p62 associated with polarization of Treg by recombinant mouse IL-33 (rmIL-33) were detected by qRT-PCR.

Results

An increased expression of IL-33/ST2 was shown in S. japonicum-infected mice. Deficiency of IL-33 or ST2 gene led to an aggravated liver pathology, which was evidenced by elevated hepatic granuloma volume, HMI and ALT levels and fibrosis, which was demonstrated by increased hepatic collagen deposition in the infected mice. Injection of rmIL-33 into the infected IL-33^−/− mice strongly abrogated the liver pathology and fibrosis, whereas no detectable effect with injecting rmIL-33 into the infected ST2^−/− mice. Furthermore, depletion of the IL-33/ST2 axis inhibited Treg, accompanied by increased Th17. rmIL-33 treatment upregulated Treg and downregulated Th17 in the infected IL-33^−/− mice, while no effect in the infected ST2^−/− mice. rmIL-33 led to elevated expressions of Atg5, Beclin-1 and inhibited expression of p62 in expansion of Treg.

Conclusion

The IL-33/ST2 axis plays a protective role in S. japonicum infected mice, which is closely related to increasing Treg responses as well as suppressing Th17 responses. Expansion of Treg by IL-33 may be associated with its regulation of autophagy.

A Novel Paradigm Based on ST2 and Its Contribution towards a Multimarker Approach in the Diagnosis and Prognosis of Heart Failure: A Prospective Study during the Pandemic Storm

Background: Acute heart failure (HF) represents an increasingly common and challenging presentation in the emergency room, also inducing a great socio-economic burden. Extensive research was conducted toward finding an ideal biomarker of acute HF, both in terms of sensitivity and specificity, but today practicians’ interest has shifted towards a more realistic multimarker approach. Natriuretic peptides (NPs) currently represent the gold standard for diagnosing HF in routine clinical practice, but novel molecules, such as sST2, emerge as potentially useful biomarkers, providing additional diagnostic and prognostic value. Methods: We conducted a prospective, single-center study that included 120 patients with acute HF and 53 controls with chronic HF. Of these, 13 patients (eight with acute HF, five from the control group) associated the coronavirus-19 disease (COVID-19). The diagnosis of HF was confirmed by a complete clinical, biological and echocardiographic approach. Results: The serum levels of all studied biomarkers (sST2, NT-proBNP, cardiac troponin) were significantly higher in the group with acute HF. By area under the curve (AUC) analysis, we noticed that NT-proBNP (AUC: 0.976) still had the best diagnostic performance, closely followed by sST2 (AUC: 0.889). However, sST2 was a significantly better predictor of fatal events, showing positive correlations for both in-hospital and at 1-month mortality rates. Moreover, sST2 was also associated with other markers of poor prognosis, such as the use of inotropes or high lactate levels, but not with left ventricle ejection fraction, age, body mass index or mean arterial pressure. sST2 levels were higher in patients with a positive history of COVID-19 as compared with non-COVID-19 patients, but the differences were statistically significant only within the control group. Bivariate regression showed a positive and linear relationship between NT-proBNP and sST2 (r(120) = 0.20, p < 0.002). Conclusions: we consider that sST2 has certain qualities worth integrating in a future multimarker test kit alongside traditional biomarkers, as it provides similar diagnostic value as NT-proBNP, but is emerging as a more valuable prognostic factor, with a better predictive value of fatal events in patients with acute HF.

IL-33 receptor expression on myeloid and plasmacytoid dendritic cells after allergen challenge in patients with allergic rhinitis

The diversity of immune responses in allergic diseases is critically mediated by dendritic cells (DCs), including myeloid and plasmacytoid DCs. Allergen inhalation increased the release of IL-33 from patients with allergic rhinitis (AR), which affecting the downstream cells by binding to its receptor (ST2). However, the effects of inhaled allergens on the expression of ST2 by DCs and IL-33 on the function of mDCs are unknown. The levels of ST2⁺mDCs and ST2⁺pDCs in the blood from patients with AR and healthy subjects were examined using flow cytometry. Moreover, the patients were challenged using the allergens and the levels of ST2⁺mDCs and ST2⁺pDCs were investigated at different time points. We found that there were higher levels of ST2⁺ mDCs and ST2⁺ pDCs in patients with AR, and these levels were further increased 0.5 h after allergen inhalation. Additionally, the type 2 immune response was upregulated after challenge. IL-33 treatment increased the expression of ST2 on mDCs. Our study demonstrated that ST2 was upregulated on DCs after allergen inhalation and that mDCs responded directly to IL-33 through ST2, suggesting that the IL-33/ST2 axis might play an important role in the pathogenesis of allergic rhinitis by DCs.

IL-33 in Rheumatic Diseases

Interleukin-33 (IL-33) is a nuclear factor mainly expressed in barrier epithelium, endothelial cells, and fibroblast reticular cells. Some inflammatory cells also express IL-33 under certain conditions. The important role of IL-33 in allergic reactions, helminth infection, cancer, tissue fibrosis, chronic inflammation, organ transplantation, and rheumatic immune diseases has been extensively studied in recent years. IL-33 primarily activates various circulating and tissue-resident immune cells, including mast cell, group 2 innate lymphoid cell (ILC2), regulatory T cell (Treg), T helper 2 cell (Th2), natural killer cell (NK cell), and macrophage. Therefore, IL-33 plays an immunomodulatory role and shows pleiotropic activity in different immune microenvironments. The IL-33/serum stimulation-2 (ST2) axis has been shown to have a detrimental effect on rheumatoid arthritis, systemic lupus erythematosus, and other rheumatic diseases. Interestingly, IL-33 also plays a protective role in the repair of barrier epithelium and the activation of Tregs. Therefore, the role of IL-33/ST2 depends on the underlying pathological conditions in rheumatic diseases. This review focuses on the dual role of the IL-33/ST2 axis in rheumatic diseases.

Autophagy inhibition facilitates wound closure partially dependent on the YAP/IL-33 signaling in a mouse model of skin wound healing

Autophagy is a self-phagocytic and highly evolutionarily conserved intracellular lysosomal catabolic system, which plays a vital role in a variety of trauma models, including skin wound healing (SWH). However, the roles and potential mechanisms of autophagy in SWH are still controversial. We firstly investigated the role of autophagy in SWH-induced wound closure rate, inflammatory response, and histopathology, utilizing an inhibitor of autophagy 3-methyladenine (3-MA) and its agonist rapamycin (RAP). As expected, we found 3-MA treatment remarkably increased the wound closure rate, combated inflammation response, and mitigated histopathological changes, while RAP delivery aggravated SWH-induced pathological damage. To further exploit the underlying mechanism of autophagy regulating inflammation, the specific inhibitors of yes-associated protein (YAP), Verteporfin, and Anti-IL-33 were applied. Herein, treating with 3-MA markedly suppressed the expression of tumor necrosis factor-α (TNF-α), IL-1β, and IL-6, promoted that of IL-10, IL-33, and ST2, while RAP administration reverted SWH-induced the up-regulation of these inflammatory cytokines mentioned above. Importantly, Verteporfin administration not only down-regulated the expression levels of YAP, TNF-α, and IL-6 but also up-regulated that of IL-33 and IL-10. Unexpectedly, 3-MA or RAP retreatment did not have any impact on the changes in IL-33 among these inflammatory indicators. Furthermore, elevated expression of IL-33 promoted wound closure and alleviated the pathological damage, whereas, its antagonist Anti-IL-33 treatment overtly reversed the above-mentioned effects of IL-33. Moreover, 3-MA in combination with anti-IL-33 treatment reversed the role of 3-MA alone in mitigated pathological changes, but they failed to revert the effect of anti-IL-33 alone on worsening pathological damage. In sum, emerging data support the novel contribution of the YAP/IL-33 pathway in autophagy inhibition against SWH-induced pathological damage, and highlight that the autophagy/YAP/IL-33 signal axis is expected to become a new therapeutic target for SWH.

Genetic Diversity of Clinical Bordetella Pertussis ST2 Strains in comparison with Vaccine Reference Strains of India

Objectives: Pertussis is a highly contagious disease of the respiratory tract caused by Bordetella pertussis, a bacterium that lives in the mouth, nose, and throat. Current study reports the highly accurate complete genomes of two clinical B. pertussis strains from India for the first time.

Methods: Complete genome sequencing was performed for two B. pertussis strains using Ion Torrent PGM and Oxford nanopore sequencing method. Data was assembled de novo and the sequence annotation was performed through PATRIC and NCBI server. Downstream analyses of the isolates were performed using CGE server databases for antimicrobial resistance genes, plasmids, and sequence types. The phylogenetic analysis was performed using Roary.

Results: The analysis revealed insertional elements flanked by IS481, which has been previously regarded as the important component for bacterial evolution. The two B. pertussis clinical strains exhibited diversity through genome degradation when compared to whole-cell vaccine reference strains of India. These isolates harboured multiple genetic virulence traits and toxin subunits, which belonged to sequence type ST2.

Conclusion: The genome information of Indian clinical B. pertussis strains will serve as a baseline data to decipher more information on the genome evolution, virulence factors and their role in pathogenesis for effective vaccine strategies.

Diagnostic significance of stimulating growth factor ST2 and N-terminal prohormone of brain natriuretic peptide NT-PROBNP in patients with ischemic heart disease in the setting of metabolic syndrome

Ischemic heart disease (IHD) is the leading cause of death and disability in many countries. The development of IHD is affected by a number of diseases, including metabolic syndrome (MS). Modern predictors of IHD include stimulating growth factor (ST2) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP).

AIM

The aim of the study was to investigate serum ST2 and NT-proBNP levels in patients with IHD and in patients with IHD in the setting of MS.

MATERIALS AND METHODS

The concentrations levels of ST2 and NTproBNP were investigated using an enzyme-linked immunoassay in 20 patients with verified IHD. 8 patients had IHD without MS (5 males, 3 females) and 10 patients had MS (9 males and 1 female). The mean age of patients was 55 ± 2 years. The control group included 20 virtually healthy, age- and gender-matched individuals.

RESULTS

Serum concentrations of ST2 in patients with IHD in the setting of MS were 31% above normal (p<0.05). In MS-free patients with IHD, serum levels of ST2 were 16% above those in controls (p<0.05). Serum concentration levels of NT-proBNP in patients with IHD in the setting of metabolic syndrome were 62% above normal (p<0.05), while NT-proBNP levels in MS-free patients with IHD were within normal (p>0.05). It was established strong positive correlations between ST2 and NT-proBNP concentration levels (r = 0.90; p<0.05).

CONCLUSIONS

Based on the completed analysis of laboratory data, a conclusion can be made that concentrations of ST2 correlates positively with NT-proBNP values in patients with IHD in the setting of MS, which may suggest the presence of ischemic and metabolic disorders in these patients.

The Role of Galectin-3 and ST2 in Cardiology: A Short Review

Galectin-3 is a lectin that binds beta-galactosides. It is involved in cardiac remodeling and fibrosis through the activation of macrophages and fibroblasts. ST2 is secreted by myocardial cells due to cardiac overload. These two biomarkers have been traditionally studied in the field of heart failure to guide medical therapy and detect the progression of the disease. Nevertheless, there are novel evidences that connect galectin-3 and ST2 with coronary heart disease and, specifically, with atrial fibrillation. The aim of this article is to concisely review the diagnostic and prognostic role of galectin-3 and ST2 in different cardiac diseases.

Signal-transducing adaptor protein-2 has a nonredundant role for IL-33-triggered mast cell activation

Signal-transducing adaptor protein (STAP)-2 is one of the STAP family adaptor proteins and ubiquitously expressed in a variety types of cells. Although STAP-2 is required for modification of FcεRI signal transduction in mast cells, other involvement of STAP-2 in mast cell functions is unknown, yet. In the present study, we mainly investigated functional roles of STAP-2 in IL-33-induced mast cell activation. In STAP-2-deficient, but not STAP-1-deficient, mast cells, IL-33-induced IL-6 and TNF-α production was significantly decreased compared with that of wild-type mast cells. In addition, STAP-2-deficiency greatly reduced TLR4-mediated mast cell activation and cytokine production. For the mechanisms, STAP-2 directly binds to IKKα after IL-33 stimulation, leading to elevated NF-κB activity. In conclusion, STAP-2, but not STAP-1, participates in IL-33-induced mast cells activation.

Sex-specific cut-off values for soluble suppression of tumorigenicity 2 (ST2) biomarker increase its cardiovascular prognostic value in the community

BACKGROUND

Suppression of tumorigenicity 2 (ST2) has important cardiovascular prognostic value in community patients; however, previous analyses have utilized non-sex specific cut-off values. We assessed whether sex-specific ST2 cut-off values would improve the prognostic utility of ST2 in the asymptomatic community.

METHODS

A total of 2042 participants underwent clinical assessment and echocardiographic evaluation. Baseline measurements of high sensitivity troponin, natriuretic peptides and ST2 were obtained in 1681 individuals. ST2, cardiac biomarkers and associated co-morbidities were evaluated by sex-specific ST2 quartile analysis. ST2 concentrations were also analysed as dichotomous variables defined as being above the sex-specific cut-off for each the outcomes of heart failure (HF), major adverse cardiac event (MACE) and mortality.

RESULTS

Median ST2 concentration was 29.4 ng/mL in male subjects and 24.1 ng/mL in female subjects. Higher ST2 concentrations were associated with incident HF (p<0.001; preserved ejection fraction (EF) p<0.001, reduced EF p=0.23), MACE (p=0.003) and mortality (p<0.001) across sex-specific quartiles. Event-based, hazard ratio (HR) analysis revealed sex-specific ST2 cut-offs were significantly more predictive of incident HF, MACE and mortality compared to non-sex-specific analysis even following adjustment for cardiac co-morbidities and traditional biomarkers.

CONCLUSIONS

These data suggest that sex-specific cut-offs, greater than non-sex specific cut-offs, significantly impact the prognostic value of the biomarker ST2 in the asymptomatic community cohort.Clinical SignificanceSuppression of tumorigenicity 2 (ST2) is a biomarker which has known associations with heart failure (HF), major adverse cardiac events (MACEs) and mortality in the general population.Recent data support the concept of sex-specific cut off values and individualized approaches based on sex to predict cardiovascular disease. Given the difference in pathobiology between the sexes, the fact that such approaches improve risk stratification is understandable. Thus, when sex-specific treatments are developed, this may similarly lead to improved outcomes.The use of sex-specific ST2 cut-off values significantly improved the prognostic value in predicting HF, MACE, and mortality in an asymptomatic community. This prognostication was particularly strong for HF with preserved ejection fraction and remained clinically significant following adjustment for cardiac co-morbidities and other traditional cardiac biomarkers (NTproBNP and hscTnI).

Expression and significance of inflammatory reactions mediated by the IL-33/ST2 signaling pathway in the serum of heart failure patients

OBJECTIVE

This research aimed to explore the clinical significance of inflammatory reactions mediated by the IL-33/ST2 signaling pathway in heart failure (HF) patients.

METHODS

A total of 100 HF patients treated in the Department of Cardiology in our hospital were prospectively regarded as the observation group, and 100 healthy age and gender matched patients who were undergoing physical examination were considered as the control group. The levels of interleukin-33 (IL-33), ST2, tumor necrosis factor-α (TNF-α) and pro B-type natriuretic peptide (pro-BNP) in the peripheral blood of patients were detected. The potential correlation between IL-33 and ST2, TNF-α and pro-BNP was analyzed by Pearson.

RESULTS

The levels of IL-33, IL-10, ST2 and pro-BNP in the peripheral blood of patients in the observation group were higher than those in the control group; and they increased with the rise of cardiac function grade (all P<0.05). In addition, IL-33 was positively correlated with TNF-α, ST2 and pro-BNP (r=0.863, 0.879, 0.945; all P<0.05). Multivariate Logistic analysis revealed that the increase of IL-33 and ST2 were independent risk factors of HF.

CONCLUSION

The IL-33 and ST2 levels in the peripheral serum of HF patients are correlated with TNF-α and BNP, the finding of which can assist in clinical diagnosis and treatment.

IL-33 Drives Expansion of Type 2 Innate Lymphoid Cells and Regulatory T Cells and Protects Mice From Severe, Acute Colitis

The hallmarks of inflammatory bowel disease are mucosal damage and ulceration, which are known to be high-risk conditions for the development of colorectal cancer. Recently, interleukin (IL)-33 and its receptor ST2 have emerged as critical modulators in inflammatory disorders. Even though several studies highlight the IL-33/ST2 pathway as a key factor in colitis, a detailed mode of action remains elusive. Therefore, we investigated the role of IL-33 during intestinal inflammation and its potential as a novel therapeutic target in colitis. Interestingly, the expression of IL-33, but not its receptor ST2, was significantly increased in biopsies from the inflamed colon of IBD patients compared to non-inflamed colonic tissue. Accordingly, in a mouse model of Dextran Sulfate Sodium (DSS) induced colitis, the secretion of IL-33 significantly accelerated in the colon. Induction of DSS colitis in ST2-/- mice displayed an aggravated colon pathology, which suggested a favorable role of the IL 33/ST2 pathway during colitis. Indeed, injecting rmIL-33 into mice suffering from acute DSS colitis, strongly abrogated epithelial damage, pro-inflammatory cytokine secretion, and loss of barrier integrity, while it induced a strong increase of Th2 associated cytokines (IL-13/IL-5) in the colon. This effect was accompanied by the accumulation of regulatory T cells (Tregs) and type 2 innate lymphoid cells (ILC2s) in the colon. Depletion of Foxp3+ Tregs during IL-33 treatment in DSS colitis ameliorated the positive effect on the intestinal pathology. Finally, IL-33 expanded ILC2s, which were adoptively transferred to DSS treated mice, significantly reduced colonic inflammation compared to DSS control mice. In summary, our results emphasize that the IL-33/ST2 pathway plays a crucial protective role in colitis by modulating ILC2 and Treg numbers.

Comparative Whole Genome Sequence Analysis and Biological Features of Clostridioides difficile Sequence Type 2‡

Clostridioides difficile sequence type 2 (ST2) has been increasingly recognized as one of the major genotypes in China, while the genomic characteristics and biological phenotypes of Chinese ST2 strains remain to be determined. We used whole-genome sequencing and phylogenetic analysis to investigate the genomic features of 182 ST2 strains, isolated between 2011 and 2017. PCR ribotyping (RT) was performed, and antibiotic resistance, toxin concentration, and sporulation capacity were measured. The core genome Maximum-likelihood phylogenetic analysis showed that ST2 strains were distinctly segregated into two genetically diverse lineages [L1 (67.0% from Northern America) and L2], while L2 further divided into two sub-lineages, SL2a and SL2b (73.5% from China). The 36 virulence-related genes were widely distributed in ST2 genomes, but in which only 11 antibiotic resistance-associated genes were dispersedly found. Among the 25 SL2b sequenced isolates, RT014 (40.0%, n = 10) and RT020 (28.0%, n = 7) were two main genotypes with no significant difference on antibiotic resistance (χ² = 0.024-2.667, P > 0.05). A non-synonymous amino acid substitution was found in tcdB (Y1975D) which was specific to SL2b. Although there was no significant difference in sporulation capacity between the two lineages, the average toxin B concentration (5.11 ± 3.20 ng/μL) in SL2b was significantly lower in comparison to those in L1 (10.49 ± 15.82 ng/μL) and SL2a (13.92 ± 2.39 ng/μL) (χ² = 12.30, P < 0.05). This study described the genomic characteristics of C. difficile ST2, with many virulence loci and few antibiotic resistance elements. The Chinese ST2 strains with the mutation in codon 1975 of the tcdB gene clustering in SL2b circulating in China express low toxin B, which may be associated with mild or moderate C. difficile infection.

The Janus Face of IL-33 Signaling in Tumor Development and Immune Escape

Simple Summary

Interleukin-33 (IL-33) is often released from damaged cells, acting as a danger signal. IL-33 exerts its function by interacting with its receptor suppression of tumorigenicity 2 (ST2) that is constitutively expressed on most immune cells. Therefore, IL-33/ST2 signaling can modulate immune responses to participate actively in a variety of pathological conditions, such as cancer. Like a two-faced Janus, which faces opposite directions, IL-33/ST2 signaling may play contradictory roles on its impact on cancer progression through both immune and nonimmune cellular components. Accumulating evidence demonstrates both pro- and anti-tumorigenic properties of IL-33, depending on the complex nature of different tumor immune microenvironments. We summarize and discuss the most recent studies on the contradictory effects of IL-33 on cancer progression and treatment, with a goal to better understanding the various ways for IL-33 as a therapeutic target.

Abstract

Interleukin-33 (IL-33), a member of the IL-1 cytokine family, plays a critical role in maintaining tissue homeostasis as well as pathological conditions, such as allergy, infectious disease, and cancer, by promoting type 1 and 2 immune responses. Through its specific receptor ST2, IL-33 exerts multifaceted functions through the activation of diverse intracellular signaling pathways. ST2 is expressed in different types of immune cells, including Th2 cells, Th1 cells, CD8⁺ T cells, regulatory T cells (T_reg), cytotoxic NK cells, group 2 innate lymphoid cells (ILC2s), and myeloid cells. During cancer initiation and progression, the aberrant regulation of the IL-33/ST2 axis in the tumor microenvironment (TME) extrinsically and intrinsically mediates immune editing via modulation of both innate and adaptive immune cell components. The summarized results in this review suggest that IL-33 exerts dual-functioning, pro- as well as anti-tumorigenic effects depending on the tumor type, expression levels, cellular context, and cytokine milieu. A better understanding of the distinct roles of IL-33 in epithelial, stromal, and immune cell compartments will benefit the development of a targeting strategy for this IL-33/ST2 axis for cancer immunotherapy.

Deficiency in ST2 signaling ameliorates RSV-associated pulmonary hypertension

Pulmonary hypertension (PH) observed during respiratory syncytial virus (RSV) bronchiolitis is associated with morbidity and mortality, especially in children with congenital heart disease. Yet, the pathophysiological mechanisms of RSV-associated PH remain unclear. Therefore, this study aimed to investigate the pathophysiological mechanism of RSV-associated PH. We used a translational mouse model of RSV-associated PH, in which wild-type (WT) and suppression of tumorigenicity 2 (ST2) knockout neonatal mice were infected with RSV at 5 days old and reinfected 4 wk later. The development of PH in WT mice following RSV reinfection was evidenced by elevated right ventricle systolic pressure, shortened pulmonary artery acceleration time (PAT), and decreased PAT/ejection time (ET) ratio. It coincided with the augmentation of periostin and IL-13 expression and increased arginase bioactivity by both arginase 1 and 2 as well as induction of nitric oxide synthase (NOS) uncoupling. Absence of ST2 signaling prevented RSV-reinfected mice from developing PH by suppressing NOS uncoupling. In summary, ST2 signaling was involved in the development of RSV-associated PH. ST2 signaling inhibition may be a novel therapeutic target for RSV-associated PH.NEW & NOTEWORTHY We report that the pathogenic role of ST2-mediated type 2 immunity and mechanisms contribute to RSV-associated pulmonary hypertension. Inhibiting ST2 signaling may be a novel therapeutic target for this condition.

Stabilization patterns and variability of hs-CRP, NT-proBNP and ST2 during 1 year after acute coronary syndrome admission: results of the BIOMArCS study

Objectives Details of the biological variability of high-sensitivity C-reactive protein (hs-CRP), N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and ST2 are currently lacking in patients with acute coronary syndrome (ACS) but are crucial knowledge when aiming to use these biomarkers for personalized risk prediction. In the current study, we report post-ACS kinetics and the variability of the hs-CRP, NT-proBNP and ST2. Methods BIOMArCS is a prospective, observational study with high frequency blood sampling during 1 year post-ACS. Using 1507 blood samples from 191 patients that remained free from adverse cardiac events, we investigated post-ACS kinetics of hs-CRP, NT-proBNP and ST2. Biological variability was studied using the samples collected between 6 and 12 months after the index ACS, when patients were considered to have stable coronary artery disease. Results On average, hs-CRP rose peaked at day 2 and rose well above the reference value. ST2 peaked immediately after the ACS but never rose above the reference value. NT-proBNP level rose on average during the first 2 days post-ACS and slowly declined afterwards. The within-subject variation and relative change value (RCV) of ST2 were relatively small (13.8%, RCV 39.7%), while hs-CRP (41.9%, lognormal RCV 206.1/-67.3%) and NT-proBNP (39.0%, lognormal RCV 185.2/-64.9%) showed a considerable variation. Conclusions Variability of hs-CRP and NT-proBNP within asymptomatic and clinically stable post-ACS patients is considerable. In contrast, within-patient variability of ST2 is low. Given the low within-subject variation, ST2 might be the most useful biomarker for personalizing risk prediction in stable post-ACS patients.

Interference of LPS H. pylori with IL-33-Driven Regeneration of Caviae porcellus Primary Gastric Epithelial Cells and Fibroblasts

Background: Lipopolysaccharide (LPS) of Helicobacter pylori (Hp) bacteria causes disintegration of gastric tissue cells in vitro. It has been suggested that interleukin (IL)-33 is involved in healing gastric injury. Aim: To elucidate whether Hp LPS affects regeneration of gastric barrier initiated by IL-33. Methods: Primary gastric epithelial cells or fibroblasts from Caviae porcellus were transfected with siRNA IL-33. Such cells, not exposed or treated with LPS Hp, were sub-cultured in the medium with or without exogenous IL-33. Then cell migration was assessed in conjunction with oxidative stress and apoptosis, activation of extracellular signal-regulated kinase (Erk), production of collagen I and soluble ST2 (IL-33 decoy). Results: Control cells not treated with LPS Hp migrated in the presence of IL-33. The pro-regenerative activity of IL-33 was related to stimulation of cells to collagen I production. Wound healing by cells exposed to LPS Hp was inhibited even in the presence of IL-33. This could be due to increased oxidative stress and apoptosis in conjunction with Erk activation, sST2 elevation and modulation of collagen I production. Conclusions: The recovery of gastric barrier cells during Hp infection potentially can be affected due to downregulation of pro-regenerative activity of IL-33 by LPS Hp.

Therapeutic Opportunities of Interleukin-33 in the Central Nervous System

Interleukin-33 (IL-33), a member of the IL-1 cytokine family, is involved in various diseases. IL-33 exerts its effects via its heterodimeric receptor complex, which comprises suppression of tumorigenicity 2 (ST2) and the IL-1 receptor accessory protein (IL-1RAP). Increasing evidence has demonstrated that IL-33/ST2 signaling plays diverse but crucial roles in the homeostasis of the central nervous system (CNS) and the pathogenesis of CNS diseases, including neurodegenerative diseases, cerebrovascular diseases, infection, trauma, and ischemic stroke. In the current review, we focus on the functional roles and cellular signaling mechanisms of IL-33 in the CNS and evaluate the potential for diagnostic and therapeutic applications.

Role of the IL-33/ST2 receptor axis in ovarian cancer progression

Ovarian cancer remains a significant health problem for women in the world due to its diagnosis at advanced stages of disease and the high mortality rate of patients. To date, ovarian cancer is frequently treated with tumor reduction surgery followed by platinum/paclitaxel-based chemotherapy; however, most patients eventually develop relapsed disease. The mRNA expression levels of interleukin-33 (IL-33) and the suppressor of tumorigenicity 2 (ST2) receptor are significantly upregulated in ovarian cancer tissues and metastatic tumor lesions. In addition, IL-33 and ST2 expression has been associated with a poor overall survival in patients with epithelial ovarian cancer. The IL-33 receptor ST2 is expressed as both a membrane-anchored receptor (ST2L) activated by IL-33, and as a soluble variant that exhibits anti-inflammatory properties. In the present review, the functions of the IL-33/ST2L axis in cells and their aberrant expression levels in ovarian cancer were discussed. In addition, targeting their expression as a novel strategy for the control of ovarian cancer progression was emphasized.

Influence of various risk factors on the level of ST2 biomarker in patients with heart failure and diabetes mellitus type 2

Heart failure (HF) despite the progress in treatment remains the main health problem worldwide. Biomarker ST2 is currently being studied in patients with HF due to its high potential predictive value and promising prospects for use as a component of biomarker-controlled therapy. The factors that can impact on the ST2 biomarker level in diabetic patients with heart failure with preserved ejection fraction (HFpEF) are still not well known.

AIM

The aim of the study was to determine the influence of various risk factors on ST2 levels in patients with HFpEF and diabetes mellitus type 2 (T2DM).

MATERIALS AND METHODS

A total of one hundred and thirty-four patients (74 females and 60 males, 51 diabetic patients and 83 patients without T2DM with HFpEF were examined. Duration of HF and T2DM, common risk factors, such as smoking, overweight, clinical examination, parameters of carbohydrate and lipid metabolism, glomerular filtration rate (GFR) and M235T polymorphism of ATG have been used. Multivariate backward stepwise cox regression analysis was performed in Statistica 10,0. p<0,05 was considered statistically significant.

RESULTS

ST2 level in patients with HFpEF associated with T2DM exceeded this value in patients with HFpEF without T2DM and was 23.26 ng/ml (18.5: 29.3) vs. 20.39 ng/ml (18.3: 24.6), respectively (p<0,05). To assess the cumulative effect of the studied factors on the ST2 level, we performed the Cox's stepwise multivariate regression analysis. Smoking, HOMA-IR (Homeostatic Model Assessment for Insulin Resistance), glucose, HbA1 and insulin levels were found to be the most significant factors influencing ST2 levels in patients with HF and T2DM, indicating a significant effect of DM type 2 on ST2 concentration.

CONCLUSIONS

Smoking, HOMA-IR, glucose, HbA1, and insulin levels can significantly affect ST2 levels in patients with T2DM and HFpEF.

Astegolimab (anti-ST2) efficacy and safety in adults with severe asthma: A randomized clinical trial

BACKGROUND

The IL-33/ST2 pathway is linked with asthma susceptibility. Inhaled allergens, pollutants, and respiratory viruses, which trigger asthma exacerbations, induce release of IL-33, an epithelial-derived "alarmin." Astegolimab, a human IgG₂ mAb, selectively inhibits the IL-33 receptor, ST2. Approved biologic therapies for severe asthma mainly benefit patients with elevated blood eosinophils (type 2-high), but limited options are available for patients with low blood eosinophils (type 2-low). Inhibiting IL-33 signaling may target pathogenic pathways in a wider spectrum of asthmatics.

OBJECTIVES

This study evaluated astegolimab efficacy and safety in patients with severe asthma.

METHODS

This double-blind, placebo-controlled, dose-ranging study (ZENYATTA [A Study to Assess the Efficacy and Safety of MSTT1041A in Participants With Uncontrolled Severe Asthma]) randomized 502 adults with severe asthma to subcutaneous placebo or 70-mg, 210-mg, or 490-mg doses of astegolimab every 4 weeks. The primary endpoint was the annualized asthma exacerbation rate (AER) at week 54. Enrollment caps ensured ∼30 patients who were eosinophil-high (≥300 cells/μL) and ∼95 patients who were eosinophil-low (<300 cells/μL) per arm.

RESULTS

Overall, adjusted AER reductions relative to placebo were 43% (P = .005), 22% (P = .18), and 37% (P = .01) for 490-mg, 210-mg, and 70-mg doses of astegolimab, respectively. Adjusted AER reductions for patients who were eosinophil-low were comparable to reductions in the overall population: 54% (P = .002), 14% (P = .48), and 35% (P = .05) for 490-mg, 210-mg, and 70-mg doses of astegolimab. Adverse events were similar in astegolimab- and placebo-treated groups.

CONCLUSIONS

Astegolimab reduced AER in a broad population of patients, including those who were eosinophil-low, with inadequately controlled, severe asthma. Astegolimab was safe and well tolerated.

A stromal progenitor and ILC2 niche promotes muscle eosinophilia and fibrosis-associated gene expression

Despite the well-accepted view that chronic inflammation contributes to the pathogenesis of Duchenne muscular dystrophy (DMD), the function and regulation of eosinophils remain an unclear facet of type II innate immunity in dystrophic muscle. We report the observation that group 2 innate lymphoid cells (ILC2s) are present in skeletal muscle and are the principal regulators of muscle eosinophils during muscular dystrophy. Eosinophils were elevated in DMD patients and dystrophic mice along with interleukin (IL)-5, a major eosinophil survival factor that was predominantly expressed by muscle ILC2s. We also find that IL-33 was upregulated in dystrophic muscle and was predominantly produced by fibrogenic/adipogenic progenitors (FAPs). Exogenous IL-33 and IL-2 complex (IL-2c) expanded muscle ILC2s and eosinophils, decreased the cross-sectional area (CSA) of regenerating myofibers, and increased the expression of genes associated with muscle fibrosis. The deletion of ILC2s in dystrophic mice mitigated muscle eosinophilia and impaired the induction of IL-5 and fibrosis-associated genes. Our findings highlight a FAP/ILC2/eosinophil axis that promotes type II innate immunity, which influences the balance between regenerative and fibrotic responses during muscular dystrophy.

Immune cells that comprise type II innate immunity coalesce to regulate tissue repair and fibrosis. Kastenschmidt et al. report that ILC2s reside in skeletal muscle, are activated in muscular dystrophy, and promote muscle eosinophilia. Stromal progenitors expressed IL-33, which expanded ILC2s and promoted a transcriptional program associated with muscle fibrosis.

Genetic Association of Interleukin 33/ST2 Polymorphisms With Behcet's Uveitis

Interleukin (IL)33, a member of the IL1 superfamily, functions as a nuclear factor and mediates biological effects by interacting with the ST2 receptor. Recent studies have described IL33 as an emerging pro-inflammatory cytokine in the immune system, and IL33/ST2 gene polymorphisms have been implicated in the pathogenesis of various immune diseases. However, the underlying mechanisms of IL33/ST2 in Behcet's disease (BD) remain to be defined. Here, we investigated the association between IL33/ST2 gene polymorphisms and BD in 585 BD uveitis (BDU) patients and 834 healthy controls using Agena MassARRAY iPLEX platform. We found that rs3821204 was associated with the development of BDU. Moreover, the frequency of rs2210463 G allele was lower in patients with genital involvement. Association analysis revealed a much greater genetic difference between complete-type and incomplete-type BD groups, including three SNPs (rs7044343, rs1048274, and rs2210463). Our findings suggest that IL33/ST2 gene polymorphisms are involved in the pathogenesis of BDU. Different genetic backgrounds may exist in complete-type and incomplete-type BD patients.

IL‑33/ST2 promotes the malignant progression of gastric cancer via the MAPK pathway

Gastric cancer (GC) remains one of the commonest malignant tumors and the second leading cause of cancer-related deaths worldwide. IL-33 is highly expressed in tumor tissues and serum of patients with GC. However, the function of the IL-33 and IL-33 receptor ST2 in the malignant progression of GC is yet to be elucidated. The present study aimed to explore the effect of the IL-33/ST2 axis on the biological functions of GC cells. The expression of ST2 in GC tissues was measured by immunohistochemistry. GC cell lines (AGS and MKN45) were treated with IL-33, and the expression of ST2 was downregulated by using specific siRNA. The effects of the IL-33/ST2 axis on cell proliferation, migration, invasion, cell cycle and apoptosis was detected by CCK8, Transwell, wound healing, flow cytometry and western blotting assays. The present study found that ST2 was highly expressed in GC tissues compared with normal tissues. IL-33 promoted the proliferation and cell cycle progression of GC cells, and upregulated the expression levels of CDK4, CDK6 and cyclin D1. Furthermore, IL-33 inhibited the apoptosis of GC cells and regulated the expression of apoptosis-associated proteins. In addition, IL-33 stimulated the invasion and migration of GC cells. However, the transfection of ST2 small interfering (si)RNA attenuated the effects of IL-33. Finally, IL-33 stimulation increased the phosphorylation levels of ERK1/2, JNK and p38. The transfection of ST2 siRNA could significantly inhibit the IL-33-induced ERK1/2, JNK and p38 activation. In conclusion, it was found that ST2 was highly expressed in GC tissues. IL-33/ST2 promoted the malignant progression of GC cells by inducing the activation of ERK1/2, JNK and p38.

Allograft or Recipient ST2 Deficiency Oppositely Affected Cardiac Allograft Vasculopathy via Differentially Altering Immune Cells Infiltration

The role of IL-33/ST2 signaling in cardiac allograft vasculopathy (CAV) is not fully addressed. Here, we investigated the role of IL-33/ST2 signaling in allograft or recipient in CAV respectively using MHC-mismatch murine chronic cardiac allograft rejection model. We found that recipients ST2 deficiency significantly exacerbated allograft vascular occlusion and fibrosis, accompanied by increased F4/80⁺ macrophages and CD3⁺ T cells infiltration in allografts. In contrast, allografts ST2 deficiency resulted in decreased infiltration of F4/80⁺ macrophages, CD3⁺ T cells and CD20⁺ B cells and thus alleviated vascular occlusion and fibrosis of allografts. These findings indicated that allografts or recipients ST2 deficiency oppositely affected cardiac allograft vasculopathy/fibrosis via differentially altering immune cells infiltration, which suggest that interrupting IL-33/ST2 signaling locally or systematically after heart transplantation leads different outcome.

Laboratory indicators of pathological changes in patients with chronic heart failure with metabolic syndrome

The presence of metabolic syndrome (MS) significantly increases the risk of developing cardiovascular diseases that lead to chronic heart failure (CHF). The values of NT-proBNP, ST-2, and CRP markers and their mutual correlations were studied in 37 patients with chronic heart failure (CHF) without metabolic syndrome (MS) (group 1) and 37 patients with CHF with MS (group 2). The aim of the study was to determine the features of their changes in patients with CHF complicated by MS, and to rank patients by assigning a rank value to the values of NTproBNP, ST2, and CRP concentrations. The average ST2 level was 51±24 ng/ml in group 1 and 62±27 ng/ml in group 2. The average values of CRP in group 1 were 23.1±5.3 mg/l, in group 2-33.0±4.4 mg/l (p<0.05). The NTproBNP level was 2413±1586 PG/ml and 2721±1635 PG/ml in groups 1 and 2, respectively. Correlations between the values of NTproBNP and ST2, NTproBNP and CRP were demonstrated. In the group of CHF with MS, compared with the group of CHF, there were significantly more patients with the most pronounced pathological levels of damage markers: the number of patients with a General rank of 6-9 in the group of CHF with MS was 59%, in the group of CHF without MS-38% (p<0.05). Of the 18 patients who died, 17 were among those who had an overall rank of 6 to 9, only 1 patient who died after hospitalization had an overall rank of 5. At the same time, among 22 patients who had improved CHF in the outcome of hospitalization, 18 patients had a total rank from 0 to 5, and in 4 patients of this category, the clinical manifestations of CHF remained virtually unchanged. The results of ranking the level of the studied laboratory markers indicate that they can be used as a predictor of various outcomes of CHF.

Optimal human pathogenic TH2 cell effector function requires local epithelial cytokine signaling

BACKGROUND

IL-33 is an emerging key factor in development of allergic diseases. The IL-33 receptor (suppressor of tumorigenicity [ST2]) is a differentially expressed gene in pathogenic T_H2 cells, but its role in T-cell effector function has not been elucidated.

OBJECTIVE

We investigated the role of IL-33 in modulating circulating allergen-specific T-cell responses. We hypothesized that selective ST2 expression on allergen-specific CD4⁺ T cells would confer susceptibility to the effects of IL-33.

METHODS

PBMCs from subjects with food allergy, inhalant allergy, and no allergy were obtained on the basis of clinical history and serum IgE level. A T-cell receptor-dependent CD154 upregulation assay and direct peptide major histocompatibility complex class II tetramer staining were used to profile allergen-specific CD4⁺ T cells by flow cytometry. Allergen-specific CD4⁺ T cell cytokine production was evaluated during IL-33 exposure. ST2 expression was also tracked by using a 2-color flow-based assay.

RESULTS

ST2 expression on peripheral allergen-specific CD4⁺ T cells was confined to subjects with allergy and restricted to T_H2A cells. Comparison between direct peptide major histocompatibility complex class II tetramer staining and the CD154 functional assay identified ST2 as a marker of T_H2A cell activation. IL-33 exposure enhanced IL-4 and IL-5 secretion in allergen-reactive T_H2A cells. Allergen-induced ST2 expression on peripheral CD4⁺ T cells can be used to track allergen-reactive T_H2A cells from donors with allergy.

CONCLUSION

ST2 expression on circulating CD4⁺ T cells represents a transient phenotype associated with T_H2A cell activation, allowing these cells to sense locally elicited tissue cytokines. IL-33 selectively amplifies pathogenic T_H2 cell effector functions, suggesting a tissue checkpoint that may regulate adaptive allergic immunity.

Activation of the Interleukin-33/ST2 Pathway Exerts Deleterious Effects in Myxomatous Mitral Valve Disease

Mitral valve disease (MVD) is a frequent cause of heart failure and death worldwide, but its etiopathogenesis is not fully understood. Interleukin (IL)-33 regulates inflammation and thrombosis in the vascular endothelium and may play a role in the atherosclerotic process, but its role in mitral valve has not been investigated. We aim to explore IL-33 as a possible inductor of myxomatous degeneration in human mitral valves. We enrolled 103 patients suffering from severe mitral regurgitation due to myxomatous degeneration undergoing mitral valve replacement. Immunohistochemistry of the resected leaflets showed IL-33 and ST2 expression in both valve interstitial cells (VICs) and valve endothelial cells (VECs). Positive correlations were found between the levels of IL-33 and molecules implicated in the development of myxomatous MVD, such as proteoglycans, extracellular matrix remodeling enzymes (matrix metalloproteinases and their tissue inhibitors), inflammatory and fibrotic markers. Stimulation of single cell cultures of VICs and VECs with recombinant human IL-33 induced the expression of activated VIC markers, endothelial–mesenchymal transition of VECs, proteoglycan synthesis, inflammatory molecules and extracellular matrix turnover. Our findings suggest that the IL-33/ST2 system may be involved in the development of myxomatous MVD by enhancing extracellular matrix remodeling.

ST2 Is a Biomarker of Pediatric Pulmonary Arterial Hypertension Severity and Clinical Worsening

BACKGROUND

Pediatric pulmonary hypertension is a severe disease defined by sustained elevation of pulmonary artery pressures and pulmonary vascular resistance (PVR). Noninvasive diagnostic and prognostic markers that are more pulmonary vascular specific have been elusive because of disease heterogeneity and patient growth.

RESEARCH QUESTION

Is soluble suppressor of tumorigenicity (ST2) associated with pulmonary hemodynamic and functional changes in pediatric pulmonary hypertension? Does ST2 improve mortality risk models in pediatric pulmonary hypertension?

STUDY DESIGN AND METHODS

Two pediatric cohorts (age < 21 years) were assayed for ST2 and N-terminal prohormone B-natriuretic peptide: a cross-sectional cohort from the National Heart Lung and Blood Institute-funded National Biological Sample and Data Repository for PAH (PAHB) (N = 182), and a second longitudinal cohort from Children's Hospital of Colorado (N = 61). Adjusted linear regression was used for association with clinical variables. Clinical mortality models (the Registry to Evaluate Early and Long-Term PAH Disease Management [REVEAL] score) with and without ST2 were used to predict worsening outcomes and compared. Pulmonary artery endothelial and smooth muscle cell ST2 expression and secretion were assayed in vitro.

RESULTS

In an adjusted (age and sex) analysis in the PAHB, ST2 was significantly associated with shorter 6-min walk distance (P = .03) and increased PVR index (P = .02). In adjusted longitudinal regression in the Children's Hospital of Colorado cohort, ST2 was significantly associated with higher PVR index (P < .001), shorter 6-min walk distance (P = .01), and higher mean pulmonary artery pressure (P < .001). Although the REVEAL Risk Score Calculator 2.0 was predictive of clinical worsening in the PAHB (hazard ratio, 1.88), addition of ST2 significantly improved the model (hazard ratio, 2.05). In cell culture, ST2 was produced and secreted predominately by endothelial cells as opposed to smooth muscle cells (P < .0001).

INTERPRETATION

In two pediatric PAH cohorts, elevated ST2 was associated with unfavorable pulmonary hemodynamics and functional measures, clinical worsening, and significantly improved prediction of clinical worsening. Pulmonary artery endothelial cellular expression of ST2 suggests that ST2 is a more pulmonary vascular-specific marker for pulmonary hypertension.

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

Interleukin (IL)-33, a member of IL-1 cytokine family, is produced by various immune cells and acts as an alarm to alert the immune system after epithelial or endothelial cell damage during cell necrosis, infection, stress, and trauma. The biological functions of IL-33 largely depend on its ligation to the corresponding receptor, suppression of tumorigenicity 2 (ST2). The pathogenic roles of this cytokine have been implicated in several disorders, including allergic disease, cardiovascular disease, autoimmune disease, infectious disease, and cancers. However, alerted levels of IL-33 may result in either disease amelioration or progression. Genetic variations of IL33 gene may confer protective or susceptibility risk in the onset of autoimmune diseases. The purpose of this review is to discuss the involvement of IL-33 and ST2 in the pathogenesis of a variety of autoimmune disorders, such as autoimmune rheumatic, neurodegenerative, and endocrine diseases.

Bloodstream infections caused by ST2 Acinetobacter baumannii: risk factors, antibiotic regimens, and virulence over 6 years period in China

Background

Bloodstream infection (BSI) caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) has been increasingly observed among hospitalized patients. The following study analyzed the epidemiology and microbiological characteristics of MDR-AB, as well as the clinical features, antimicrobial treatments, and outcomes in patients over a six years period in China.

Methods

This retrospective study was conducted in a large tertiary hospital in China between January 2013 and December 2018. The clinical and microbiological data of all consecutive hospitalized patients with MDR-AB induced bloodstream infection were included and analyzed.

Results

A total of 108 BSI episodes were analyzed. All MDR isolates belonged to ST2, a sequence type that has spread all over the world. Overall, ST2 strains showed strong biofilm formation ability, high serum resistance, and high pathogenicity. As for the clinical characteristics of the patient, 30-day mortality was 69.4% (75/108). The three main risk factors included mechanical ventilation, intensive care unit (ICU) stay, and thrombocytopenia; three protective factors included a change of antimicrobial regimen within 48 h after positive blood culture, use of the antibacterial agent combination, and more inpatient days. The most effective antibacterial regimen was the combination of cefoperazone/sulbactam and tigecycline.

Conclusions

BSI caused by ST2 A.baumannii represents a difficult challenge for physicians, considering the high mortality associated with this infection. The combination of cefoperazone/sulbactam and tigecycline may be an effective treatment option.

Gender-Related Differences in Heart Failure Biomarkers

Important differences in comorbidities and clinical characteristics exist between women and men with heart failure (HF). In particular, differences in the kinetics of biological circulating biomarkers—a critical component of cardiovascular care—are highly relevant. Most circulating HF biomarkers are assessed daily by clinicians without taking sex into account, despite the multiple gender-related differences observed in plasma concentrations. Even in health, compared to men, women tend to exhibit higher levels of natriuretic peptides and galectin-3 and lower levels of cardiac troponins and the cardiac stress marker, soluble ST2. Many biological factors can provide a reliable explanation for these differences, like body composition, fat distribution, or menopausal status. Notwithstanding, these sex-specific differences in biomarker levels do not reflect different pathobiological mechanisms in HF between women and men, and they do not necessarily imply a need to use different diagnostic cut-off levels in clinical practice. To date, the sex-specific prognostic value of HF biomarkers for risk stratification is an unresolved issue that future research must elucidate. This review outlines current evidence regarding gender-related differences in circulating biomarkers widely used in HF, the pathophysiological mechanisms underlying these differences, and their clinical relevance.

Detection of the agr System and Resistance to Antimicrobials in Biofilm-Producing S. epidermidis

The ability of Staphylococcus epidermidis to produce virulence factors, such as biofilm, added to its increased resistance to antimicrobials can cause infections that are difficult to treat. Many staphylococcal virulence factors are under the control of the accessory gene regulator (agr). The objective of this study was to establish the agr locus and susceptibility of biofilm-producing S. epidermidis specimens to antimicrobial agents, through PCR reactions, reverse transcription polymerase chain reaction (RT-PCR), and the determination of minimum inhibitory concentration (MIC), and to analyze the clonal profile of 300 strains isolated from blood culture specimens from inpatients at a University Hospital in Brazil, over a 20-year period by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) techniques. The ica operon expression was shown in 83.6% strains, bhp gene in 11.5%, and aap gene in 32.8%. Oxacillin resistance was detected in 90.1%, while 4.9% showed tigecycline resistance, and intermediate resistance to quinupristin/dalfopristin was identified in 0.4%. Clonal profile determination showed 11 clusters, with the ST2 type determined as the major cluster. The S. epidermidis biofilm producer demonstrated a predominance of agr I locus, oxacillin resistance, and SCCmec III as well as the potential dissemination of pathogenic clones in hospital settings over long periods.

ST2 expression and release by the bronchial epithelium is downregulated in asthma

BACKGROUND

The airway epithelium plays an important role in wound repair, host defense and is involved in the immunopathogenesis of asthma. Genome wide association studies have described associations between ST2/Interleukin (IL)-33 genes in asthma, but its role in bronchial epithelium is unclear.

METHODS

ST2 expression was examined in subjects with asthma and healthy controls in bronchial epithelium from biopsies (n = 27 versus n = 9) and brushings (n = 34 versus n = 20) by immunohistochemistry and RNA-Seq. In human primary bronchial epithelial cells ST2 mRNA and protein expression were assessed by qPCR, flow cytometry, Western blotting, and immunofluorescence. IL-33 function in epithelial cells was examined by intracellular calcium measurements, wound healing assays, and synthetic activation by gene array and ELISA.

RESULTS

Bronchial epithelial ST2 protein expression was significantly decreased in biopsies in subjects with asthma compared to healthy controls (P = .039). IL1RL1 gene expression in bronchial brushes was not different between health and disease. In vitro primary bronchial epithelial cells expressed ST2 and IL-33 stimulation led to an increase in intracellular calcium, altered gene expression, but had no effect upon wound repair. Epithelial cells released sST2 spontaneously, which was reduced following stimulation with TNFα or poly-IC. Stimulation by TNFα or poly-IC did not affect the total ST2 expression by epithelial cell whereas surface ST2 decreased in response to TNFα, but not poly-IC.

CONCLUSION

In asthma, bronchial epithelium protein expression of ST2 is decreased. Our in vitro findings suggest that this decrease might be a consequence of the pro-inflammatory environment in asthma or in response to viral infection.

Interleukin-33 Promotes Serotonin Release from Enterochromaffin Cells for Intestinal Homeostasis

The gastrointestinal tract is known as the largest endocrine organ that encounters and integrates various immune stimulations and neuronal responses due to constant environmental challenges. Enterochromaffin (EC) cells, which function as chemosensors on the gut epithelium, are known to translate environmental cues into serotonin (5-HT) production, contributing to intestinal physiology. However, how immune signals participate in gut sensation and neuroendocrine response remains unclear. Interleukin-33 (IL-33) acts as an alarmin cytokine by alerting the system of potential environmental stresses. We here demonstrate that IL-33 induced instantaneous peristaltic movement and facilitated Trichuris muris expulsion. We found that IL-33 could be sensed by EC cells, inducing release of 5-HT. IL-33-mediated 5-HT release activated enteric neurons, subsequently promoting gut motility. Mechanistically, IL-33 triggered calcium influx via a non-canonical signaling pathway specifically in EC cells to induce 5-HT secretion. Our data establish an immune-neuroendocrine axis in calibrating rapid 5-HT release for intestinal homeostasis.

Blockade of IL-33 signalling attenuates osteoarthritis

Objectives

Osteoarthritis (OA) is the most common form of arthritis characterised by cartilage degradation, synovitis and pain. Disease modifying treatments for OA are not available. The critical unmet need is to find therapeutic targets to reduce both disease progression and pain. The cytokine IL‐33 and its receptor ST2 have been shown to play a role in immune and inflammatory diseases, but their role in osteoarthritis is unknown.

Methods

Non‐OA and OA human chondrocytes samples were examined for IL‐33 and ST2 expression. Novel inducible cartilage specific knockout mice (IL‐33^{Acan CreERT2}) and inducible fibroblast‐like synoviocyte knockout mice (IL‐33^{Col1a2 CreERT2}) were generated and subjected to an experimental OA model. In addition, wild‐type mice were intra‐articularly administered with either IL‐33‐ or ST2‐neutralising antibodies during experimental OA studies.

Results

IL‐33 and its receptor ST2 have increased expression in OA patients and a murine disease model. Administering recombinant IL‐33 increased OA and pain in vivo. Synovial fibroblast‐specific deletion of IL‐33 decreased synovitis but did not impact disease outcomes, whilst cartilage‐specific deletion of IL‐33 improved disease outcomes in vivo. Blocking IL‐33 signalling also reduced the release of cartilage‐degrading enzymes in human and mouse chondrocytes. Most importantly, we show the use of monoclonal antibodies against IL‐33 and ST2 attenuates both OA and pain in vivo.

Conclusion

Overall, our data reveal blockade of IL‐33 signalling as a viable therapeutic target for OA.