IL-33/ST2 Axis in Organ Fibrosis

Combined inhibition of IL-1, IL-33 and IL-36 signalling by targeting IL1RAP ameliorates skin and lung fibrosis in preclinical models of systemic sclerosis

BACKGROUND

The interleukin (IL)-1 receptor accessory protein (IL1RAP) is an essential coreceptor required for signalling through the IL-1, IL-33 and IL-36 receptors. Here, we investigate the antifibrotic potential of the combined inhibition of these cytokines by an anti-IL1RAP antibody to provide a scientific background for clinical development in systemic sclerosis (SSc).

METHODS

The expression of IL1RAP-associated signalling molecules was determined by data mining of publicly available RNA sequencing (RNAseq) data as well as by imaging mass cytometry. The efficacy of therapeutic dosing of anti-IL1RAP antibodies was determined in three complementary mouse models: sclerodermatous chronic graft-versus-host disease (cGvHD), bleomycin-induced dermal fibrosis model and topoisomerase-I (topo)-induced fibrosis.

RESULTS

SSc skin showed upregulation of IL1RAP and IL1RAP-related signalling molecules on mRNA and protein level compared with normal skin. IL-1, IL-33 and IL-36 all regulate distinct gene sets related to different pathophysiological processes in SSc. The responses of human fibroblasts and endothelial cells to IL-1, IL-33 and IL-36 were completely blocked by treatment with an anti-IL1RAP antibody in vitro. Moreover, anti-IL1RAP antibody treatment reduced dermal and pulmonary fibrosis in cGvHD-induced, bleomycin-induced and topoisomerase-induced fibrosis. Importantly, RNAseq analyses revealed effects of IL1RAP inhibition on multiple processes related to inflammation and fibrosis that are also deregulated in human SSc skin.

CONCLUSION

This study provides the first evidence for the therapeutic benefits of targeting IL1RAP in SSc. Our findings have high translational potential as the anti-IL1RAP antibody CAN10 has recently entered a phase one clinical trial.

Soluble ST2: A Novel Biomarker for Diagnosis and Prognosis of Cardiovascular Disease

The increasing incidence of cardiovascular disease (CVD) is a significant global health concern, affecting millions of individuals each year. Accurate diagnosis of acute CVD poses a formidable challenge, as misdiagnosis can significantly decrease patient survival rates. Traditional biomarkers have played a vital role in the diagnosis and prognosis of CVDs, but they can be influenced by various factors, such as age, sex, and renal function. Soluble ST2 (sST2) is a novel biomarker that is closely associated with different CVDs. Its low reference change value makes it suitable for continuous measurement, unaffected by age, kidney function, and other confounding factors, facilitating risk stratification of CVDs. Furthermore, the combination of sST2 with other biomarkers can enhance diagnostic accuracy and prognostic value. This review aims to provide a comprehensive overview of sST2, focusing on its diagnostic and prognostic value as a myocardial marker for different types of CVDs and discussing the current limitations of sST2.

Heterozygous Spink1 c.194+2T>C mutation promotes chronic pancreatitis after acute attack in mice

BACKGROUND & AIMS

Mutations in genes, including serine protease inhibitor Kazal-type 1 (SPINK1), influence disease progression following sentinel acute pancreatitis event (SAPE) attacks. SPINK1 c.194+2T > C intron mutation is one of the main mutants of SPINK1，which leads to the impairment of SPINK1 function by causing skipping of exon 3. Research on the pathogenesis of SAPE attacks would contribute to the understanding of the outcomes of acute pancreatitis. Therefore, the aim of the study was to clarify the role of SPINK1 c.194+2T > C mutation in the CP progression after an AP attack.

METHODS

SAPE attacks were induced in wildtype and SPINK mutant (Spink1 c.194+2T > C) mice by cerulein injection. The mice were sacrificed at 24 h, 14 d, 28 d, and 42 d post-SAPE. Data-independent acquisition (DIA) proteomic analysis was performed for the identification of differentially expressed protein in the pancreatic tissues. Functional analyses were performed using THP-1 and HPSCs.

RESULTS

Following SAPE attack, the Spink1 c.194+2T > C mutant mice exhibited a more severe acute pancreatitis phenotype within 24 h. In the chronic phase, the chronic pancreatitis phenotype was more severe in the Spink1 c.194+2T > C mutant mice after SAPE. Proteomic analysis revealed elevated IL-33 level in Spink1 c.194+2T > C mutant mice. Further in vitro analyses revealed that IL-33 induced M2 polarization of macrophages and activation of pancreatic stellate cells.

CONCLUSION

Spink1 c.194+2T > C mutation plays an important role in the prognosis of patients following SAPE. Heterozygous Spink1 c.194+2T > C mutation promotes the development of chronic pancreatitis after an acute attack in mice through elevated IL-33 level and the induction of M2 polarization in coordination with pancreatic stellate cell activation.

Single-cell mass cytometry in immunological skin diseases

Immune-related skin diseases represent a collective of dermatological disorders intricately linked to dysfunctional immune system processes. These conditions are primarily characterized by an immoderate activation of the immune system or deviant immune responses, involving diverse immune components including immune cells, antibodies, and inflammatory mediators. However, the precise molecular dysregulation underlying numerous individual cases of these diseases and unique subsets respond under disease conditions remains elusive. Comprehending the mechanisms and determinants governing the homeostasis and functionality of diseases could offer potential therapeutic opportunities for intervention. Mass cytometry enables precise and high-throughput quantitative measurement of proteins within individual cells by utilizing antibodies labeled with rare heavy metal isotopes. Imaging mass cytometry employs mass spectrometry to obtain spatial information on cell-to-cell interactions within tissue sections, simultaneously utilizing more than 40 markers. The application of single-cell mass cytometry presents a unique opportunity to conduct highly multiplexed analysis at the single-cell level, thereby revolutionizing our understanding of cell population heterogeneity and hierarchy, cellular states, multiplexed signaling pathways, proteolysis products, and mRNA transcripts specifically in the context of many autoimmune diseases. This information holds the potential to offer novel approaches for the diagnosis, prognostic assessment, and monitoring responses to treatment, thereby enriching our strategies in managing the respective conditions. This review summarizes the present-day utilization of single-cell mass cytometry in studying immune-related skin diseases, highlighting its advantages and limitations. This technique will become increasingly prevalent in conducting extensive investigations into these disorders, ultimately yielding significant contributions to their accurate diagnosis and efficacious therapeutic interventions.

Serum alarmins and the risk of incident interstitial lung disease in rheumatoid arthritis

OBJECTIVES

To quantify associations of serum alarmins with risk of rheumatoid arthritis-associated interstitial lung disease (RA-ILD).

METHODS

Using serum collected at enrolment, three alarmins (IL-33, thymic stromal lymphopoietin [TSLP] and IL-25) were measured in a multicentre prospective RA cohort. ILD was classified using systematic medical record review. Cross-sectional associations of log-transformed (IL-33, TSLP) or quartile (IL-25) values with RA-ILD at enrolment (prevalent RA-ILD) were examined using logistic regression, while associations with incident RA-ILD developing after enrolment were examined using Cox proportional hazards. Covariates in multivariate models included age, sex, race, smoking status, RA disease activity score and anti-cyclic citrullinated antibody positivity.

RESULTS

Of 2835 study participants, 115 participants (4.1%) had prevalent RA-ILD at baseline and an additional 146 (5.1%) developed incident ILD. There were no associations between serum alarmin concentrations and prevalent ILD in unadjusted or adjusted logistic regression models. In contrast, there was a significant inverse association between IL-33 concentration and the risk of developing incident RA-ILD in unadjusted (hazard ratio [HR] 0.73 per log-fold increase; 95% CI: 0.57, 0.95; P = 0.018) and adjusted (HR 0.77; 95% CI: 0.59, 1.00; P = 0.047) models. No significant associations of TSLP or IL-25 with incident ILD were observed.

CONCLUSION

In this study, we observed a significant inverse association between serum IL-33 concentration and the risk of developing incident RA-ILD, but no associations with prevalent ILD. Additional investigation is required to better understand the mechanisms driving this relationship and how serum alarmin IL-33 assessment might contribute to clinical risk stratification in patients with RA.

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.

Mitochondrial GRIM19 Loss Induces Liver Fibrosis through NLRP3/IL33 Activation via Reactive Oxygen Species/NF-кB Signaling

Background and Aims

Hepatic fibrosis (HF) is a critical step in the progression of hepatocellular carcinoma (HCC). Gene associated with retinoid-IFN-induced mortality 19 (GRIM19), an essential component of mitochondrial respiratory chain complex I, is frequently attenuated in various human cancers, including HCC. Here, we aimed to investigate the potential relationship and underlying mechanism between GRIM19 loss and HF pathogenesis.

Methods

GRIM19 expression was evaluated in normal liver tissues, hepatitis, hepatic cirrhosis, and HCC using human liver disease spectrum tissue microarrays. We studied hepatocyte-specific GRIM19 knockout mice and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9) lentivirus-mediated GRIM19 gene-editing in murine hepatocyte AML12 cells in vitro and in vivo. We performed flow cytometry, immunofluorescence, immunohistochemistry, western blotting, and pharmacological intervention to uncover the potential mechanisms underlying GRIM19 loss-induced HF.

Results

Mitochondrial GRIM19 was progressively downregulated in chronic liver disease tissues, including hepatitis, cirrhosis, and HCC tissues. Hepatocyte-specific GRIM19 heterozygous deletion induced spontaneous hepatitis and subsequent liver fibrogenesis in mice. In addition, GRIM19 loss caused chronic liver injury through reactive oxygen species (ROS)-mediated oxidative stress, resulting in aberrant NF-кB activation via an IKK/IкB partner in hepatocytes. Furthermore, GRIM19 loss activated NLRP3-mediated IL33 signaling via the ROS/NF-кB pathway in hepatocytes. Intraperitoneal administration of the NLRP3 inhibitor MCC950 dramatically alleviated GRIM19 loss-driven HF in vivo.

Conclusions

The mitochondrial GRIM19 loss facilitates liver fibrosis through NLRP3/IL33 activation via ROS/NF-кB signaling, providing potential therapeutic approaches for earlier HF prevention.

Inflammation accelerating intestinal fibrosis: from mechanism to clinic

Intestinal fibrosis is a prevalent complication of IBD that that can frequently be triggered by prolonged inflammation. Fibrosis in the gut can cause a number of issues, which continue as an ongoing challenge to healthcare systems worldwide. The primary causes of intestinal fibrosis are soluble molecules, G protein-coupled receptors, epithelial-to-mesenchymal or endothelial-to-mesenchymal transition, and the gut microbiota. Fresh perspectives coming from in vivo and in vitro experimental models demonstrate that fibrogenic pathways might be different, at least to some extent, independent of the ones that influence inflammation. Understanding the distinctive procedures of intestinal fibrogenesis should provide a realistic foundation for targeting and blocking specific fibrogenic pathways, estimating the risk of fibrotic consequences, detecting early fibrotic alterations, and eventually allowing therapy development. Here, we first summarize the inflammatory and non-inflammatory components of fibrosis, and then we elaborate on the underlying mechanism associated with multiple cytokines in fibrosis, providing the framework for future clinical practice. Following that, we discuss the relationship between modernization and disease, as well as the shortcomings of current studies. We outline fibrosis diagnosis and therapy, as well as our recommendations for the future treatment of intestinal fibrosis. We anticipate that the global review will provides a wealth of fresh knowledge and suggestions for future fibrosis clinical practice.

The IL-33-ST2 axis plays a vital role in endometriosis via promoting epithelial-mesenchymal transition by phosphorylating β-catenin

OBJECTIVES

Interleukin 33 (IL-33) is a crucial inflammatory factor that functions as an alarm signal in endometriosis (EMs). Epithelial-mesenchymal transition (EMT), a process related to inflammatory signals, intracellular reactive oxygen species (ROS) production, and lipid peroxidation, have been proposed as potential mechanisms that contribute to the development and progression of EMs. IL-33 is highly upregulated in the ectopic milieu. Moreover, ectopic endometrial cells constitutively express interleukin-33 receptor ST2 (IL-33R). However, the role of IL-33/ST2 in the EMT of EMs remains largely unknown. In this study, we aimed to mechanistically determine the role of IL-33/ST2 in EMs-associated fibrosis.

MATERIALS AND METHODS

We established a non-lethal oxidative stress model to explore the conditions that trigger IL-33 induction. We performed α-smooth muscle actin (α-SMA) protein detection, cell counting kit-8 (CCK-8) assays, and scratch assays to analyze the impact of IL-33 on primary endometrial stromal cells (ESCs) proliferation and invasion. Clinical samples from patients with or without EMs were subjected to immunohistochemical (IHC) and and immunofluorescence(IF) staining to assess the clinical relevance of IL-33 receptor ST2 and EMT-related proteins. Furthermore, we used the ectopic human endometrial epithelial cell line 12Z and normal human epithelial cell line EEC to evaluate the effects of IL-33 on Wnt/β-catenin signaling. The effect of IL-33 on EMT-associated fibrosis was validated in vivo by intraperitoneal injections of IL-33 and antiST2.

RESULTS

We observed that ectopic milieu, characterized by ROS, TGF-β1, and high level of estrogen, triggers the secretion of IL-33 from ectopic ESCs. Ectopic endometrial lesions exhibited higher level of fibrotic characteristics and ST2 expression than that in the normal endometrium. Exogenous recombinant human (rhIL-33) enhanced ESC migration and survival. Similarly, 12Z cells displayed a higher degree of EMT characteristics with elevated expression of CCN4 and Fra-1, downstream target genes of the WNT/β-catenin pathway, than that observed in EECs. Conversely, blocking IL-33 with neutralizing antibodies, knocking down ST2 or β-catenin with siRNA, and β-catenin dephosphorylation abolished its effects on EMT promotion. In vivo validation demonstrated that IL-33 significantly promotes EMs-related fibrosis through the activation of Wnt/β-catenin signaling.

CONCLUSION

Our data strongly support the vital role of the IL-33/ST2 pathway in EMs-associated fibrosis and emphasize the importance of the EMT in the pathophysiology of fibrosis. Targeting the IL-33/ST2/Wnt/β-catenin axis may hold promise as a feasible therapeutic approach for controlling fibrosis in EMs.

IL27 and IL1RN are causally associated with acute pancreatitis: a Mendelian randomization study

BACKGROUND

The interleukin (IL) plays a role in the development of acute pancreatitis (AP). However, the specific IL in AP has not been fully revealed. Therefore, the association between prospective IL and AP was studied via Mendelian randomization (MR).

METHODS

The HUGO Gene nomenclature committee (HGNC) database provided 47 interleukin related genes (ILRGs). ILRGs and differentially expressed genes (DEGs) from GSE194331 were overlapped to create differently expressed ILRGs (DE-ILRGs). The integrative epidemiology unit (IEU) open genome-wide association study (GWAS) database provided exposure and outcome datasets. Univariate MR (UVMR) analysis using MR-Egger, IVW, simple mode, and weighted mode was done. UVMR results were verified using sensitivity analysis. Drug prediction, MVMR analysis, and PPI network development were also performed.

RESULTS

Six DE-ILRGs were obtained. IL27 and IL1RN were substantially causally linked with AP by UVMR analysis (OR = 0.926, P < 0.001 and OR = 1.031, P = 0.023). Our sensitivity analysis showed the dependability of our results. Direct effect of IL27 was suggested by MVMR analysis. In the cytokine receptor binding pathway, IL27 and IL1RN interacted with IL36G and IL1R2. TAE-684, ARQ-680, and 12 other IL1RN and 14 IL27 medications were predicted.

CONCLUSIONS

IL1RN was identified as a risk factor for acute pancreatitis (AP), but IL27 was found to be a protective factor for AP.

Precision Cardio-oncology: Update on Omics-Based Diagnostic Methods

OPINION STATEMENT

Cardio-oncology is an emerging interdisciplinary field dedicated to the early detection and treatment of adverse cardiovascular events associated with anticancer treatment, and current clinical management of anticancer-treatment-related cardiovascular toxicity (CTR-CVT) remains limited by a lack of detailed phenotypic data. However, the promise of diagnosing CTR-CVT using deep phenotyping has emerged with the development of precision medicine, particularly the use of omics-based methodologies to discover sensitive biomarkers of the disease. In the future, combining information produced by a variety of omics methodologies could expand the clinical practice of cardio-oncology. In this review, we demonstrate how omics approaches can improve our comprehension of CTR-CVT deep phenotyping, discuss the positive and negative aspects of available omics approaches for CTR-CVT diagnosis, and outline how to integrate multiple sets of omics data into individualized monitoring and treatment. This will offer a reliable technical route for lowering cardiovascular morbidity and mortality in cancer patients and survivors.

Gene expression of cytokines and prostaglandin metabolism-related proteins in eosinophilic otitis media

The objective of this study was to investigate the levels of gene expression in the middle ear mucosa of 2 patients diagnosed with eosinophilic otitis media. One patient with severe hearing loss showed high expression levels of genes encoding IL-5 and IL-33 receptors.

Fibrosis in IBD: from pathogenesis to therapeutic targets

BACKGROUND

Intestinal fibrosis resulting in stricture formation and obstruction in Crohn's disease (CD) and increased wall stiffness leading to symptoms in ulcerative colitis (UC) is among the largest unmet needs in inflammatory bowel disease (IBD). Fibrosis is caused by a multifactorial and complex process involving immune and non-immune cells, their soluble mediators and exposure to luminal contents, such as microbiota and environmental factors. To date, no antifibrotic therapy is available. Some progress has been made in creating consensus definitions and measurements to quantify stricture morphology for clinical practice and trials, but approaches to determine the degree of fibrosis within a stricture are still lacking.

OBJECTIVE

We herein describe the current state of stricture pathogenesis, measuring tools and clinical trial endpoints development.

DESIGN

Data presented and discussed in this review derive from the past and recent literature and the authors' own research and experience.

RESULTS AND CONCLUSIONS

Significant progress has been made in better understanding the pathogenesis of fibrosis, but additional studies and preclinical developments are needed to define specific therapeutic targets.

The diagnostic value of sST2 for myocardial fibrosis in idiopathic inflammatory myopathies in subclinical stage of cardiac involvement

OBJECTIVE

Myocardial fibrosis occurs in the early subclinical stage of cardiac involvement in idiopathic inflammatory myopathies (IIMs). Soluble suppression of tumorigenicity 2 (sST2) is known to have an immunomodulatory impact during autoimmune disease development. The current study investigated the diagnostic value of sST2 for myocardial fibrosis during early stage of cardiac involvement in IIM.

METHODS

A total of 44 IIM patients with normal heart function and 32 age- and gender-matched healthy controls (HCs) were enrolled. Serum sST2 levels were measured by ELISA and cardiac magnetic resonance (CMR) parameters for myocardial fibrosis [native T1, extracellular volume (ECV), late-gadolinium enhancement (LGE)] and oedema (T2 values) were analysed.

RESULTS

IIM patients had significantly higher sST2 levels than HCs [67.5 ng/ml (s.d. 30.4)] vs 14.4 (5.5), P < 0.001] and levels correlated positively with diffuse myocardial fibrosis parameters, native T1 (r = 0.531, P = 0.000), ECV (r = 0.371, P = 0.013) and focal myocardial fibrosis index and LGE (r = 0.339, P = 0.024) by Spearman's correlation analysis. sST2 was an independent predictive factor for diffuse and focal myocardial fibrosis after adjustment for age, gender, BMI and ESR. Risk increased ≈15.4% for diffuse [odds ratio (OR) 1.154 (95% CI 1.021, 1.305), P = 0.022] and 3.8% for focal [OR 1.038 (95% CI 1.006, 1.072), P = 0.020] myocardial fibrosis per unit increase of sST2. Cut-off values for diagnosing diffuse and focal myocardial fibrosis were sST2 ≥51.3 ng/ml [area under the curve (AUC) = 0.942, sensitivity = 85.7%, specificity = 98.9%, P < 0.001] and 53.3 ng/ml (AUC = 0.753, sensitivity = 87.5%, specificity = 58.3%, P < 0.01), respectively.

CONCLUSION

sST2 showed a marked elevation during the subclinical stage of cardiac involvement in IIM and has potential as a biomarker for predicting diffuse and focal myocardial fibrosis in IIM.

Recent advances in intestinal fibrosis

Despite many progresses have been made in the treatment of inflammatory bowel disease, especially due to the increasing number of effective therapies, the development of tissue fibrosis is a very common occurrence along the natural history of this condition. To a certain extent, fibrogenesis is a physiological and necessary process in all those conditions characterised by chronic inflammation. However, the excessive deposition of extracellular matrix within the bowel wall will end up in the formation of strictures, with the consequent need for surgery. A number of mechanisms have been described in this process, but some of them are not yet clear. For sure, the main trigger is the presence of a persistent inflammatory status within the mucosa, which in turn favours the occurrence of a pro-fibrogenic environment. Among the main key players, myofibroblasts, fibroblasts, immune cells, growth factors and cytokines must be mentioned. Although there are no available therapies able to target fibrosis, the only way to prevent it is by controlling inflammation. In this review, we summarize the state of art of the mechanisms involved in gut fibrogenesis, how to diagnose it, and which potential targets could be druggable to tackle fibrosis.

IL-33/soluble ST2 axis is associated with radiation-induced cardiac injury

Radiotherapy for treating breast cancer is associated with cardiac damage. This study aimed to investigate the role of the interleukin (IL)-33/soluble receptor ST2 (sST2) axis in radiation-induced cardiac injury. Expressions of IL-33 and sST2 were detected in breast cancer patients following radiotherapy, radiation-induced cardiac damaged mice model, and cardiomyocytes using quantitative real-time PCR (qRT-PCR) and immunohistochemical assay. Cardiac injury was evaluated through an ultrasound imaging system and hematoxylin & eosin staining. The transcriptional factor was assessed using dual-luciferase reporter assay and chromatin immunoprecipitation. The results indicated that IL-33 and sST2 were highly expressed in breast cancer patients, which further elevated post-6 months but reduced after 12 months of radiotherapy. Radiation induces cardiac dysfunction and elevated IL-33 and sST2 levels in a time-dependent manner. However, silencing of IL-33 decreased sST2 expression to alleviate radiation-induced cardiac dysfunction. The IL-33 could be transcriptional activated by TCF7L2 by binding to IL33 promoter sites, which mutation alleviated cardiomyocyte injury caused by radiation. Additionally, radiation treatment resulted in higher levels of TCF7L2, IL-33, and sST2 in cardiomyocytes, and TCF7L2 knockdown reduced IL-33 and sST2 expression. In conclusion, TCF7L2 transcriptional-activated IL-33 mediated sST2 to regulate radiation-induced cardiac damage, providing novel insights into radiotherapy-induced cardiac damage.

The IL-33/ST2 axis is protective against acute inflammation during the course of periodontitis

Periodontitis, which is induced by repeated bacterial invasion and the ensuing immune reactions that follow, is the leading cause of tooth loss. Periodontal tissue is comprised of four different components, each with potential role in pathogenesis, however, most studies on immune responses focus on gingival tissue. Here, we present a modified ligature-induced periodontitis model in male mice to analyze the pathogenesis, which captures the complexity of periodontal tissue. We find that the inflammatory response in the peri-root tissues and the expression of IL-6 and RANKL by Thy-1.2- fibroblasts/stromal cells are prominent throughout the bone destruction phase, and present already at an early stage. The initiation phase is characterized by high levels of ST2 (encoded by Il1rl1) expression in the peri-root tissue, suggesting that the IL-33/ST2 axis is involved in the pathogenesis. Both Il1rl1- and Il33-deficient mice exhibit exacerbated bone loss in the acute phase of periodontitis, along with macrophage polarization towards a classically activated phenotype and increased neutrophil infiltration, indicating a protective role of the IL-33/ST2 axis in acute inflammation. Thus, our findings highlight the hidden role of the peri-root tissue and simultaneously advance our understanding of the etiology of periodontitis via implicating the IL-33/ST2 axis.

Biomaterial-based mechanical regulation facilitates scarless wound healing with functional skin appendage regeneration

Scar formation resulting from burns or severe trauma can significantly compromise the structural integrity of skin and lead to permanent loss of skin appendages, ultimately impairing its normal physiological function. Accumulating evidence underscores the potential of targeted modulation of mechanical cues to enhance skin regeneration, promoting scarless repair by influencing the extracellular microenvironment and driving the phenotypic transitions. The field of skin repair and skin appendage regeneration has witnessed remarkable advancements in the utilization of biomaterials with distinct physical properties. However, a comprehensive understanding of the underlying mechanisms remains somewhat elusive, limiting the broader application of these innovations. In this review, we present two promising biomaterial-based mechanical approaches aimed at bolstering the regenerative capacity of compromised skin. The first approach involves leveraging biomaterials with specific biophysical properties to create an optimal scarless environment that supports cellular activities essential for regeneration. The second approach centers on harnessing mechanical forces exerted by biomaterials to enhance cellular plasticity, facilitating efficient cellular reprogramming and, consequently, promoting the regeneration of skin appendages. In summary, the manipulation of mechanical cues using biomaterial-based strategies holds significant promise as a supplementary approach for achieving scarless wound healing, coupled with the restoration of multiple skin appendage functions.

Fibroblasts and immune cells: at the crossroad of organ inflammation and fibrosis

The immune and fibrotic responses have evolved to work in tandem to respond to pathogen clearance and promote tissue repair. However, excessive immune and fibrotic responses lead to chronic inflammation and fibrosis, respectively, both of which are key pathological drivers of organ pathophysiology. Fibroblasts and immune cells are central to these responses, and evidence of these two cell types communicating through soluble mediators or adopting functions from each other through direct contact is constantly emerging. Here, we review complex junctions of fibroblast-immune cell cross talk, such as immune cell modulation of fibroblast physiology and fibroblast acquisition of immune cell-like functions, as well as how these systems of communication contribute to organ pathophysiology. We review the concept of antigen presentation by fibroblasts among different organs with different regenerative capacities, and then focus on the inflammation-fibrosis axis in the heart in the complex syndrome of heart failure. We discuss the need to develop anti-inflammatory and antifibrotic therapies, so far unsuccessful to date, that target novel mechanisms that sit at the crossroads of the fibrotic and immune responses.

Evaluation of soluble suppression of tumorigenicity 2 (sST2) as serum marker for liver fibrosis

BACKGROUND & AIMS

With the increase in patients at risk of advanced liver disease due to the obesity epidemic, there will be a need for simple screening tools for advanced liver fibrosis. Soluble suppression of tumorigenicity 2 (sST2) is a serum biomarker for fibrotic processes. The aim of this study was to evaluate sST2 as marker for liver fibrosis in patients successfully treated for chronic hepatitis C.

METHODS

424 patients from the Swiss Hepatitis C Cohort Study were screened for inclusion in this post-hoc cohort study. Inclusion criteria were sustained virological response (SVR), available elastography (VCTE) and serum samples for biomarker analysis before and after treatment. For the validation of sST2, values were compared to VCTE, FIB-4 and APRI using Spearman's correlation and AUROC analyses.

RESULTS

Data of 164 subjects were finally analyzed. Median sST2 values slightly increased with VCTE-derived fibrosis stages and remained stable after reaching SVR within the respective fibrosis stage, suggesting that sST2 is not influenced by liver inflammation. However, correlation of sST2 pre- and post-treatment with VCTE was fair (Spearman's rho = 0.39 and rho = 0.36). The area under the curve (AUROC) for sST2 in detecting VCTE-defined F4 fibrosis (vs. F0-F3) before therapy was 0.74 (95%CI 0.65-0.83), and 0.67(95%CI 0.56-0.78) for the discrimination of F3/F4 fibrosis vs. F0-F2. Adding sST2 to either APRI or FIB-4, respectively, increased diagnostic performance of both tests.

CONCLUSIONS

sST2 can potentially identify patients with advanced fibrosis as a single serum marker and in combination with APRI and FIB-4.

Predictive value of soluble suppression of tumorigenicity 2 in atrial fibrillation: a systematic review and meta-analysis

Purpose

Atrial fibrosis is the main pathological basis for the pathogenesis and progression of atrial fibrillation (AF). Soluble suppression of tumorigenicity 2 (sST2) is involved in fibrosis. Recent studies have explored its predictive value in AF outcomes. We performed this study to assess whether sST2 is an independent biomarker of AF outcomes and explore the potential mechanism.

Methods

PubMed, Web of Science, EMBASE, and Cochrane Library databases were searched systematically from inception through July 1, 2023, to identify relevant studies. Outcomes of interest included occurrence, recurrence, and major adverse cardiac events (MACEs) of AF. This meta-analysis was reported following the criteria outlined in PRISMA 2020, and the protocol was registered in PROSPERO (number: CRD42023459789). All statistical analyses were performed using the STATA version 16.

Result

Twenty four studies with 14,755 patients were included in the meta-analysis. The meta-analyses found that sST2 was significantly associated with the risk of occurrence [HR:1.04, 95% CI: 1.02-1.07, P < 0.01; I2 = 67.8%], recurrence [HR:1.09, 95% CI: 1.02-1.16, P < 0.01; I2 = 89.5%], and MACEs (HR:1.60, 95% CI: 1.13-2.27, P < 0.01; I2 = 82.0%) of AF. Furthermore, patients with AF showed higher sST2 than controls without AF (SMD: 0.41, 95% CI: 0.27-0.54, P < 0.01; I2 = 0%), and AF patients with recurrence after catheter ablation (CA) showed significantly higher sST2 than those without recurrence (SMD: 0.81, 95% CI: 0.33-1.28, P < 0.01; I2 = 83.9%). Sensitivity analyses showed that the outcomes were stable.

Conclusions

Higher sST2 was association with an increased risk of occurrence, recurrence, and MACEs of AF. Assessing sST2 can be used as a potential screening method to predict AF outcomes.

Systematic Review Registration

PROSPERO (CRD42023459789).

A Narrative Review of Cytokine Networks: Pathophysiological and Therapeutic Implications for Inflammatory Bowel Disease Pathogenesis

Inflammatory bowel disease (IBD) is a lifelong inflammatory immune mediated disorder, encompassing Crohn's disease (CD) and ulcerative colitis (UC); however, the cause and specific pathogenesis of IBD is yet incompletely understood. Multiple cytokines produced by different immune cell types results in complex functional networks that constitute a highly regulated messaging network of signaling pathways. Applying biological mechanisms underlying IBD at the single omic level, technologies and genetic engineering enable the quantification of the pattern of released cytokines and new insights into the cytokine landscape of IBD. We focus on the existing literature dealing with the biology of pro- or anti-inflammatory cytokines and interactions that facilitate cell-based modulation of the immune system for IBD inflammation. We summarize the main roles of substantial cytokines in IBD related to homeostatic tissue functions and the remodeling of cytokine networks in IBD, which may be specifically valuable for successful cytokine-targeted therapies via marketed products. Cytokines and their receptors are validated targets for multiple therapeutic areas, we review the current strategies for therapeutic intervention and developing cytokine-targeted therapies. New biologics have shown efficacy in the last few decades for the management of IBD; unfortunately, many patients are nonresponsive or develop therapy resistance over time, creating a need for novel therapeutics. Thus, the treatment options for IBD beyond the immune-modifying anti-TNF agents or combination therapies are expanding rapidly. Further studies are needed to fully understand the immune response, networks of cytokines, and the direct pathogenetic relevance regarding individually tailored, safe and efficient targeted-biotherapeutics.

Dermatophagoides Pteronyssinus 1 (DerP1) May Trigger NLRP3-Mediated Corneal Epithelial Cell Pyroptosis by Elevating Interleukin-33 Expression Levels

PURPOSE

To characterize the in vivo effects of Dermatophagoides pteronyssinus 1 (DerP1) in mice and determine the underlying NLRP3 inflammasome-mediated pyroptosis signaling mechanisms in the human corneal epithelial cells (HCECs).

METHODS

DerP1 was used to induce allergic conjunctivitis in C57 mice. HCECs were sensitized with DerP1 in vitro to mimic their condition observed in allergic conjunctivitis in vivo. Transmission electron microscopy was used to evaluate pyroptosis in the HCECs, enzyme-linked immunosorbent assays to assess interleukin (IL)-33, IL-1β and IL-4 levels, flow cytometry to detect the proportion of Th2 cells, MTT assays to assess cell metabolic activity, immunofluorescence to evaluate the effects of DerP1 on functional HCEC phenotypes, and Western blot assays to detect the expression of NOD-like receptor family pyrin domain-containing 3 (NLRP3), gasdermin D (GSDMD), N-terminal fragment of GSDMD (GSDMD-N), pro-caspase-1, cleaved caspase-1, IL-1β, and IL-33. IL-33 expression in the HCECs was knocked down via lentivirus transfection.

RESULTS

In vivo, DerP1 promotes pyroptosis, production of Th2 inflammatory cytokines and IL-33, and NLRP3 activation in mouse corneas. In vitro, pyroptotic bodies were found in the HCECs after sensitization with DerP1. Various concentrations of DerP1 increased the expression levels of NLRP3, GSDMD, GSDMD-N, pro-caspase-1, cleaved caspase-1, and IL-1β in the HCECs, with the largest increase observed after exposure to 20 µM DerP1. In vitro, recombinant human IL-33 mediated the expression of pyroptotic biomarkers in the HCECs, whereas IL-33 silencing diminished 20 µM DerP1-induced increase in their expression levels.

CONCLUSIONS

DerP1 induces pyroptosis and allergic conjunctivitis, the expression of Th2 inflammatory cytokines, NLRP3 activation, and IL-33 in mouse corneas in our model. These effects would attribute to its activating NLRP3-GSDMD signaling pathway axis via enhancing IL-33 expression in HCECs.

ILC2 influence the differentiation of alveolar type II epithelial cells in bronchopulmonary dysplasia mice

Bronchopulmonary dysplasia, a common complication of premature infants, is mainly characterized by blocked alveolarization. Proverbially, the injury of alveolar type II epithelial cells is regarded as the pathologic basis of occurrence and development of bronchopulmonary dysplasia. In the case of alveolar epithelial damage, alveolar type II epithelial cells can also differentiate to alveolar type I epithelial cells as progenitor cells. During bronchopulmonary dysplasia, the differentiation of alveolar type II epithelial cells becomes abnormal. Group 2 innate lymphoid cells can produce type 2 cytokines in response to a variety of stimuli, including the epithelial cytokines IL-25, IL-33, and thymic stromal lymphopoietin. Previous studies have shown that group 2 innate lymphoid cells can inhibit the alveolarization process of bronchopulmonary dysplasia by secreting IL-13. However, whether group 2 innate lymphoid cells can affect the differentiation of alveolar type II epithelial cells in the pathologic process of bronchopulmonary dysplasia remains unclear. In this study, we have shown that IL-13 secreted by group 2 innate lymphoid cells increased during bronchopulmonary dysplasia, which was related to the release of large amounts of IL-33 by impaired alveolar type II epithelial cells. This led to abnormal differentiation of alveolar type II epithelial cells, reduced differentiation to alveolar type I epithelial cells, and increased transdifferentiation to mesenchymal cells through the epithelial-mesenchymal transition. Taken together, our study provides a complementary understanding of the development of bronchopulmonary dysplasia and highlights a novel immune mechanism in the pathogenesis of bronchopulmonary dysplasia.

Soluble suppression of tumorigenicity 2 associated with atrial fibrillation detected after stroke: A retrospective study

Background

The soluble suppression of tumorigenicity 2 (sST2) is closely associated with stroke and atrial fibrillation (AF). However, no studies on sST2 and AF detected after stroke (AFDAS) have been reported. This study investigated the correlation between sST2 and AFDAS.

Methods

This was a single-center, retrospective, clinical observational study. Patients diagnosed with a transient ischemic attack (TIA) or acute ischemic stroke were enrolled, and all patients underwent sST2 detection and electrocardiogram (ECG) or Holter monitoring for at least 24 h.

Results

In total, 970 patients were enrolled, including 72 (7.4 %) with AFDAS. Multivariate analysis showed that age (OR 1.078; 95 % CI, 1.050-1.107; p < 0.001), heart rate (HR) (OR 1.025; 95 % CI, 1.007-1.044; p = 0.007), national institutes of health stroke scale (NIHSS) score (OR 1.089; 95 % CI, 1.029-1.152; p = 0.003), high sensitivity C-reactive protein (hs-CRP) (OR 1.006; 95 % CI, 1.002-1.009; p = 0.001), and sST2 (OR 1.018; 95 % CI, 1.010-1.026; p < 0.001) were independent risk factors of AFDAS. The areas under the curve (AUCs) for age, HR, sST2, hs-CRP, and NIHSS were 0.731, 0.599, 0.815, 0.664, and 0.700, respectively. The conventional model included age, HR, NIHSS score, and hs-CRP level based on multivariate results. After adding sST2 to the model, the model's performance in predicting AFDAS increased significantly.

Conclusion

Higher sST2 levels were associated with the occurrence of AFDAS. Thus, sST2 can improve the risk model for AFDAS.

Altered Blood Molecular Markers of Cardiovascular Function in Rats after Intrauterine Hypoxia and Drug Therapy

Many children and adults who have suffered prenatal hypoxia at an early age develop many serious diseases. This disease is an actual problem of pediatric cardiology and little studied. The aim was to analyze the cardioprotective effect of L-arginine, Thiotriazoline, Angioline, and Mildronate on the cardiovascular system of rats after prenatal hypoxia. Methods: The experiments were carried out on 50 female white rats; intraperitoneal sodium nitrite solution was administered daily to pregnant female rats after 16 days at a dose of 50 mg/kg. Control pregnant rats received saline. The offspring were divided into groups: 1-intact; 2-the control group of rat pups after PH, treated daily with physiological saline; 3-six groups of rat pups after PH, treated daily from the 1st to the 30th day after birth. Heat shock protein HSP70 was determined by enzyme immunoassay, ST2 Nitrotyrosine, and eNOS was observed by ELISA. Results: Angiolin showed a high cardioprotective effect even a month after discontinuation of the drug, and after introduction, the highest decrease in ST2 nitrotyrosine was revealed. Thiotriazoline and L-arginine have an antioxidant effect and a positive effect on eNOS expression, increasing the concentration of HSP70. Mildronate increased the expression of eNOS and the concentration of HSP70 in the blood of experimental rats after a course of administration, but did not show an antioxidant effect and did not reduce the concentration of nitrotyrosine. The results obtained indicate the cardioprotective effect of modulators of the NO system with different mechanisms of action of drugs after prenatal hypoxia.

The Role of the IL-33/ST2 Axis in CpG-Induced Macrophage Activation Syndrome

Background

Macrophage activation syndrome (MAS) is a fatal inflammatory condition, which is often associated with the elevation of multiple proinflammatory cytokines and multiple organ dysfunction. Previous studies have shown that ST2 contributes to T cell overactivation and plays a detrimental role in mouse models of primary hemophagocytic lymphohistiocytosis. The purpose of this study was to investigate the role of the IL-33/ST2 axis in a mouse model of MAS induced by repeated injections of cytosine-phosphate-guanine (CpG).

Methods

Serum cytokines were determined using the cytometric bead array by flow cytometry. IL-33 and ST2 were detected by immunohistochemistry and real-time quantitative PCR in the liver and spleen of mice. CD3 and F4/80 in the liver were detected by immunohistochemistry. Inflammatory macrophages and effector memory T lymphocytes were detected by flow cytometry.

Result

The CpG-induced MAS model was successfully induced after repeated CpG injections, presenting with hypercytokinemia and hepatosplenomegaly. The numbers of IL-33 positive cells in the liver and spleen decreased significantly, while the expression of ST2 in the liver tended to increase in the mice with MAS. IL-33 and St2 knockout mice showed similar levels of hepatosplenomegaly, peripheral blood count, and cytokine storm when compared with wild-type (WT) mice after induction of MAS. There were also no significant differences in liver pathology (including inflammatory cell infiltration of CD3 and F4/80) and levels of splenic inflammatory macrophages and effector memory T cells between the WT and knockout mice.

Conclusion

These results suggested that IL-33 decreased in the liver and spleen tissues of MAS mice. Further results suggest that IL-33 and St2 knockout mice have no treatment potential in CpG-induced MAS. Thus, the IL-33/ST2 axis has little effect on the prognosis of CpG-induced MAS.

Inflammation-mediated fibroblast activation and immune dysregulation in collagen VII-deficient skin

Inflammation is known to play a critical role in all stages of tumorigenesis; however, less is known about how it predisposes the tissue microenvironment preceding tumor formation. Recessive dystrophic epidermolysis bullosa (RDEB), a skin-blistering disease secondary to COL7A1 mutations and associated with chronic wounding, inflammation, fibrosis, and cutaneous squamous cell carcinoma (cSCC), models this dynamic. Here, we used single-cell RNA sequencing (scRNAseq) to analyze gene expression patterns in skin cells from a mouse model of RDEB. We uncovered a complex landscape within the RDEB dermal microenvironment that exhibited altered metabolism, enhanced angiogenesis, hyperproliferative keratinocytes, infiltration and activation of immune cell populations, and inflammatory fibroblast priming. We demonstrated the presence of activated neutrophil and Langerhans cell subpopulations and elevated expression of PD-1 and PD-L1 in T cells and antigen-presenting cells, respectively. Unsupervised clustering within the fibroblast population further revealed two differentiation pathways in RDEB fibroblasts, one toward myofibroblasts and the other toward a phenotype that shares the characteristics of inflammatory fibroblast subsets in other inflammatory diseases as well as the IL-1-induced inflammatory cancer-associated fibroblasts (iCAFs) reported in various cancer types. Quantitation of inflammatory cytokines indicated dynamic waves of IL-1α, TGF-β1, TNF, IL-6, and IFN-γ concentrations, along with dermal NF-κB activation preceding JAK/STAT signaling. We further demonstrated the divergent and overlapping roles of these cytokines in inducing inflammatory phenotypes in RDEB patients as well as RDEB mouse-derived fibroblasts together with their healthy controls. In summary, our data have suggested a potential role of inflammation, driven by the chronic release of inflammatory cytokines such as IL-1, in creating an immune-suppressed dermal microenvironment that underlies RDEB disease progression.

Dickkopf1 Promotes Pulmonary Fibrosis upon Bleomycin-Induced Lung Injury

Orchestration of inflammation and tissue repair processes is critical to maintaining homeostasis upon tissue injury. Tissue fibrosis is a pathological process characterized by aberrant accumulation of extracellular matrix proteins, such as collagen, upon injury. Dickkopf1 (DKK1) is a quintessential Wnt antagonist. The role of DKK1 in bleomycin (BLM)-induced lung injury and fibrosis model remains elusive. This study shows that BLM-induced lung injury markedly elevated DKK1 protein expressions in the lungs in mice, consistent with human pulmonary fibrosis patient lung tissues. The elevated DKK1 levels coincided with immune cell infiltration and collagen deposition. Notably, the reduced expression of DKK1 in Dkk1 hypomorphic doubleridge (Dkk1d/d) mice abrogated BLM-induced lung inflammation and fibrosis. Immune cell infiltration, collagen deposition, expression of profibrotic cytokine transforming growth factor β1 (TGF-β1), and extracellular matrix protein-producing myofibroblast marker α-smooth muscle actin (α-SMA) were reduced in Dkk1d/d mice. Consistent with these results, local DKK1 antibody administration after BLM-induced lung injury substantially decreased lung inflammation and fibrosis phenotypes. Taken together, these results demonstrate that DKK1 is a proinflammatory and profibrotic ligand that promotes inflammation and fibrosis upon BLM-induced lung injury, placing it as an attractive molecular target for dysregulated pulmonary inflammation and tissue repair.

A Deep View of the Biological Property of Interleukin-33 and Its Dysfunction in the Gut

Intestinal diseases have always posed a serious threat to human health, with inflammatory bowel disease (IBD) being one of them. IBD is an autoimmune disease characterized by chronic inflammation, including ulcerative colitis (UC) and Crohn's disease (CD). The "alarm" cytokine IL-33, which is intimately associated with Th2 immunity, is a highly potent inflammatory factor that is considered to have dual functions-operating as both a pro-inflammatory cytokine and a transcriptional regulator. IL-33 has been shown to play a crucial role in both the onset and development of IBD. Therefore, this review focuses on the pathogenesis of IBD, the major receptor cell types, and the activities of IL-33 in innate and adaptive immunity, as well as its underlying mechanisms and conflicting conclusions in IBD. We have also summarized different medicines targeted to IL-33-associated diseases. Furthermore, we have emphasized the role of IL-33 in gastrointestinal cancer and parasitic infections, giving novel prospective therapeutic utility in the future application of IL-33.

IL33-mediated NPM1 promotes fibroblast-to-myofibroblast transition via ERK/AP-1 signaling in silica-induced pulmonary fibrosis

Silicosis is a global occupational pulmonary disease due to the accumulation of silica dust in the lung. Lacking effective clinical drugs makes the treatment of this disease quite challenging in clinics largely because the pathogenic mechanisms remain obscure. Interleukin 33 (IL33), a pleiotropic cytokine, could promote wound healing and tissue repair via the receptor ST2. However, the mechanisms governing the involvement of IL33 in silicosis progression remain to be further explored. Here, we demonstrated that the IL33 levels in the lung sections were significantly overexpressed after bleomycin and silica treatment. Chromatin immunoprecipitation assay, knockdown, and reverse experiments were performed in lung fibroblasts to prove gene interaction following exogenous IL33 treatment or cocultured with silica-treated lung epithelial cells. Mechanistically, we illustrated that silica-stimulated lung epithelial cells secreted IL33 and further promoted the activation, proliferation, and migration of pulmonary fibroblasts by activating the ERK/AP-1/NPM1 signaling pathway in vitro. And more, treatment with NPM1 siRNA-loaded liposomes markedly protected mice from silica-induced pulmonary fibrosis in vivo. In conclusion, the involvement of NPM1 in the progression of silicosis is regulated by the IL33/ERK/AP-1 signaling axis, which is the potential therapeutic target candidate in developing novel antifibrotic strategies for pulmonary fibrosis.

IL-33's role in the gut immune system: A comprehensive review of its crosstalk and regulation

The intestinal tract is the largest immune organ in the human body, comprising a complex network of immune cells and epithelial cells that perform a variety of functions such as nutrient absorption, digestion, and waste excretion. Maintenance of homeostasis and effective responses to injury in the colonic epithelium are crucial for maintaining homeostasis between these two cell types. The onset and perpetuation of gut inflammation, characterizing inflammatory bowel diseases (IBD), are triggered by constitutive dysregulation of cytokine production. IL-33 is a newly characterized cytokine that has emerged as a critical modulator of inflammatory disorders. IL-33 is constitutively expressed in the nuclei of different cell types such as endothelial, epithelial, and fibroblast-like cells. Upon tissue damage or pathogen encounter, IL-33 is released as an alarmin and signals through a heterodimer receptor that consists of serum Stimulation-2 (ST2) and IL-1 receptor accessory protein (IL-1RAcP). IL-33 has the ability to induce Th2 cytokine production and enhance both Th1 and Th2, as well as Th17 immune responses. Exogenous administration of IL-33 in mice caused pathological changes in most mucosal tissues such as the lung and the gastrointestinal (GI) tract associated with increased production of type 2 cytokines and chemokines. In vivo and in vitro, primary studies have exhibited that IL-33 can activate Th2 cells, mast cells, or basophils to produce type 2 cytokines such as IL-4, IL-5, and IL-13. Moreover, several novel cell populations, collectively referred to as "type 2 innate lymphoid cells," were identified as being IL-33 responsive and are thought to be important for initiating type 2 immunity. Nevertheless, the underlying mechanisms by which IL-33 promotes type 2 immunity in the GI tract remain to be fully understood. Recently, it has been discovered that IL-33 plays important roles in regulatory immune responses. Highly suppressive ST2 + FoxP3+ Tregs subsets regulated by IL-33 were identified in several tissues, including lymphoid organs, gut, lung, and adipose tissues. This review aims to comprehensively summarize the current knowledge on IL-33's role in the gut immune system, its crosstalk, and regulation. The article will provide insights into the potential applications of IL-33-based therapies in the treatment of gut inflammatory disorders.

The gut-lung axis: Mendelian randomization identifies a causal association between inflammatory bowel disease and interstitial lung disease

BACKGROUND

Previous studies have suggested the association between interstitial lung disease (ILD) and inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC).

OBJECTIVES

To examine the potential bidirectional causal relationship between IBD and ILD using the Mendelian randomization (MR) method.

METHODS

We obtained the data from the genome-wide association studies (GWASs) in European individuals for IBD (25,042 cases and 34,915 controls) and ILD (21,806 cases and 196,986 controls) from the IEU GWAS database. We screened for instrumental variables based on the three assumptions of MR. The two-sample bidirectional MR analysis was performed using the inverse-variance weighted method and multiple sensitivity analyses.

RESULTS

Genetic liability to IBD was significantly associated with an increased ILD risk (odds ratio (OR) = 1.20, 95% confidence interval (CI) = 1.17-1.24, p = 3.67E-33). When considering the IBD subtypes, ILD risk was associated with genetic liability to both CD (OR = 1.14, 95% CI = 1.10-1.17, p = 1.91E-17) and UC (OR = 1.16, 95% CI = 1.12-1.21, p = 3.51E-13). There was weak evidence for the effect of genetic liability to ILD on IBD (OR = 1.32, 95% CI = 0.99-1.76, p = 0.062), CD (OR = 1.25, 95% CI = 1.00-1.55, p = 0.046), and UC (OR = 1.47, 95%CI = 1.01-2.14, p = 0.046).

CONCLUSION

The results indicate a strong causal effect of IBD (including CD and UC) on ILD.

Serum and bronchoalveolar lavage fluid levels of soluble B7H3 in patients with interstitial lung diseases

BACKGROUND

The B7 family member B7H3/CD276 was recently reported to be involved in the pathophysiology of idiopathic pulmonary fibrosis (IPF). However, the association of B7H3 with prognosis in patients with fibrosing interstitial lung diseases (ILDs), including IPF, remains unclear. This study was investigated to determine the potential of soluble B7H3 (sB7H3) as a biomarker to predict prognosis in patients with fibrosing ILDs.

METHODS

Patients with ILDs from various categories who underwent bronchoalveolar lavage (BAL) were included in the study. The relationship between sB7H3 levels in serum or BAL fluid (BALF) and clinical variables at the time of ILD diagnosis was studied retrospectively. All patients who met the fibrosing ILD criteria were followed for 5 years.

RESULTS

We found that coexisting malignancy affected the serum, but not the BALF, sB7H3 levels. There was no significant correlation between serum and BALF levels of sB7H3 in 49 ILD patients without malignancy (11 with sarcoidosis, 5 with drug-induced ILD, 22 with IPF, and 11 with ILD associated with systemic sclerosis). We also found that the BALF levels, but not serum levels, of sB7H3 at the time of ILD diagnosis had independent prognostic potential on 5-year survival in patients with fibrosing ILDs. Of note, patients with a higher level of BALF sB7H3 at diagnosis (≥0.100 ng/mL) showed significantly shorter survival than those with lower levels.

CONCLUSIONS

This study suggests that BALF sB7H3 could be a novel prognostic biomarker in a broad range of fibrosing ILD patients.

The IL-33:ST2 axis is unlikely to play a central fibrogenic role in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) with limited treatment options. Interleukin-33 (IL-33) is proposed to play a role in the development of IPF however the exclusive use of prophylactic dosing regimens means that the therapeutic benefit of targeting this cytokine in IPF is unclear.

METHODS

IL-33 expression was assessed in ILD lung sections and human lung fibroblasts (HLFs) by immunohistochemistry and gene/protein expression and responses of HLFs to IL-33 stimulation measured by qPCR. In vivo, the fibrotic potential of IL-33:ST2 signalling was assessed using a murine model of bleomycin (BLM)-induced pulmonary fibrosis and therapeutic dosing with an ST2-Fc fusion protein. Lung and bronchoalveolar lavage fluid were collected for measurement of inflammatory and fibrotic endpoints. Human precision-cut lung slices (PCLS) were stimulated with transforming growth factor-β (TGFβ) or IL-33 and fibrotic readouts assessed.

RESULTS

IL-33 was expressed by fibrotic fibroblasts in situ and was increased by TGFβ treatment in vitro. IL-33 treatment of HLFs did not induce IL6, CXCL8, ACTA2 and COL1A1 mRNA expression with these cells found to lack the IL-33 receptor ST2. Similarly, IL-33 stimulation had no effect on ACTA2, COL1A1, FN1 and fibronectin expression by PCLS. Despite having effects on inflammation suggestive of target engagement, therapeutic dosing with the ST2-Fc fusion protein failed to reduce BLM-induced fibrosis measured by hydroxyproline content or Ashcroft score.

CONCLUSIONS

Together these findings suggest the IL-33:ST2 axis does not play a central fibrogenic role in the lungs with therapeutic blockade of this pathway unlikely to surpass the current standard of care for IPF.

Theroleofinterleukin-1familyinfibroticdiseases

Fibrosis refers to the phenomenon that fibrous connective tissues are increased and parenchymal cells are decreased in organs or tissues such as lung, heart, liver, kidney, skin and so on. It usually occurs at the late stage of repair of chronic or recurrent tissue damage. Fibrotic disease is the main factor for the morbidity and mortality of all tissues and organ systems. Long-term fibrosis can lead to organ and tissue dysfunction and even failure. Interleukin -1 family cytokines are a series of classical inflammatory factors and involved in the occurrence and development process of multiple fibrotic diseases, its biological function, relationship with diseases and application are more and more favored by scientists from various countries. So far, 11 cytokines and 10 receptors of IL-1 family have been identified. In this paper, the cytokines, receptors, signaling pathways and biological functions of IL-1 family are summarized, and the correlation with fibrosis diseases is analyzed.

An emerging role of inflammasomes in spinal cord injury and spinal cord tumor

Spinal cord injury (SCI) and spinal cord tumor are devastating events causing structural and functional impairment of the spinal cord and resulting in high morbidity and mortality; these lead to a psychological burden and financial pressure on the patient. These spinal cord damages likely disrupt sensory, motor, and autonomic functions. Unfortunately, the optimal treatment of and spinal cord tumors is limited, and the molecular mechanisms underlying these disorders are unclear. The role of the inflammasome in neuroinflammation in diverse diseases is becoming increasingly important. The inflammasome is an intracellular multiprotein complex and participates in the activation of caspase-1 and the secretion of pro-inflammatory cytokines such as interleukin (IL)-1β and IL-18. The inflammasome in the spinal cord is involved in the stimulation of immune-inflammatory responses through the release of pro-inflammatory cytokines, thereby mediating further spinal cord damage. In this review, we highlight the role of inflammasomes in SCI and spinal cord tumors. Targeting inflammasomes is a promising therapeutic strategy for the treatment of SCI and spinal cord tumors.

Engineered fibrotic liver-targeted truncated transforming growth factor β receptor type II variant for superior anti-liver fibrosis therapy

Truncated transforming growth factor β receptor type II (tTβRII) is a promising anti-liver fibrotic candidate because it serves as a trap for binding excessive TGF-β1 by means of competing with wild type TβRII (wtTβRII). However, the widespread application of tTβRII for the treatment of liver fibrosis has been limited by its poor fibrotic liver-homing capacity. Herein, we designed a novel tTβRII variant Z-tTβRII by fusing the platelet-derived growth factor β receptor (PDGFβR)-specific affibody Z_PDGFβR to the N-terminus of tTβRII. The target protein Z-tTβRII was produced using Escherichia coli expression system. In vitro and in vivo studies showed that Z-tTβRII has a superior specific fibrotic liver-targeting potential via the engagement of PDGFβR-overexpressing activated hepatic stellate cells (aHSCs) in liver fibrosis. Moreover, Z-tTβRII significantly inhibited cell migration and invasion, and downregulated fibrosis- and TGF-β1/Smad pathway-related protein levels in TGF-β1-stimiluated HSC-T6 cells. Furthermore, Z-tTβRII remarkably ameliorated liver histopathology, mitigated the fibrosis responses and blocked TGF-β1/Smad signaling pathway in CCl₄-induced liver fibrotic mice. More importantly, Z-tTβRII exhibits a higher fibrotic liver-targeting potential and stronger anti-fibrotic effects than either its parent tTβRII or former variant BiPPB-tTβRII (PDGFβR-binding peptide BiPPB modified tTβRII). In addition, Z-tTβRII shows no significant sign of potential side effects in other vital organs in liver fibrotic mice. Taken together, we conclude that Z-tTβRII with its a high fibrotic liver-homing potential, holds a superior anti-fibrotic activity in liver fibrosis in vitro and in vivo, which may be a potential candidate for targeted therapy for liver fibrosis.

Nicotine exposure exacerbates silica-induced pulmonary fibrosis via STAT3-BDNF-TrkB-mediated epithelial-mesenchymal transition in alveolar type II cells

The addictive substance nicotine, found in cigarettes and some e-cigarettes, plays a vital role in pro-inflammatory and fibrotic processes. However, the part played by nicotine in the progression of silica-induced pulmonary fibrosis is poorly understood. We used mice exposed to both silica and nicotine to investigate whether nicotine synergizes with silica particles to worsen lung fibrosis. The results revealed that nicotine accelerated the development of pulmonary fibrosis in silica-injured mice by activating STAT3-BDNF-TrkB signalling. Mice with a history of exposure to nicotine showed an increase in Fgf7 expression and alveolar type II cell proliferation if they were also exposed to silica. However, newborn AT2 cells could not regenerate the alveolar structure and release pro-fibrotic factor IL-33. Moreover, activated TrkB induced the expression of p-AKT, which promotes the expression of epithelial-mesenchymal transcription factor Twist, but no Snail. In vitro assessment confirmed activation of the STAT3-BDNF-TrkB pathway in AT2 cells, exposed to nicotine plus silica. In addition, TrkB inhibitor K252a downregulated p-TrkB and the downstream p-AKT and restricted the epithelial-mesenchymal transition caused by nicotine plus silica. In conclusion, nicotine activates the STAT3-BDNF-TrkB pathway, which promotes epithelial-mesenchymal transition and exacerbates pulmonary fibrosis in mice with combined exposure to silica particles and nicotine.

Serum-soluble ST2 and systemic sclerosis arthropathy

Interleukin (IL)33 and its receptor ST2 have been involved in the pathogenesis of several conditions, including arthritis. The aim of the study was to evaluate the association between IL33 or soluble ST2 (sST2) serum levels and systemic sclerosis (SSc) articular involvement. IL33 and sST2 serum levels were measured in 64 SSc patients and 24 HC matched for sex and age. Articular involvement assessed by using Disease Activity Score 28 based on erythrocyte sedimentation rate (DAS28-ESR), presence of tendon friction rubs (TFRs) and finger-to-palm (FTP) distance. sST2 serum levels were significantly higher in SSc patients with DAS28-ESR > 3.2 than in SSc patients with DAS28-ESR⩽3.2 [9726.1 (IQR 7746.5 - 14,953.5) pg/mL vs 7611.7 (IQR 5162.6 -11,036.7) pg/mL; p < 0.05]. sST2 serum levels were significantly higher in SSc patients with TFRs compared to SSc patients without TFRs [9726.1 (IQR 7746.5 - 14,953.5) pg/mL vs 7426.4 (IQR 5145.9 - 10,593.5) pg/mL; p < 0.01] and in SSc patients with FTP ≥ 1 cm compared to SSc patients with FTP < 1 cm [9683.7 (IQR 8067.2 - 16,387.6) pg/mL vs 7679.1 (IQR 5246.1 - 11,472.2) pg/mL; p < 0.05]. No significant association was observed between IL33 and DAS28-ESR, TFRs and FTP. A slightly positive linear correlation was found between sST2 and Disease Activity Index (r = 0.294, p < 0.05) and Disease Severity Scale (r = 0.265, p < 0.05). sST2 serum levels were positively correlated with DAS28-ESR (r = 0.371, p < 0.01). Elevated sST2 serum levels were associated with higher articular disease activity, TFRs and hand dysfunction, suggesting that sST2 might have a role in the pathogenesis of SSc articular involvement. Key Points • In SSc patients elevated serum levels of sST2 were associated with higher articular disease activity • High serum levels of sST2 were reported in SSc patients with TFRs and hand dysfunction • sST2 might have a role in the pathogenesis of SSc articular involvement.

Tissue injury and leukocyte changes in post-acute sequelae of SARS-CoV-2: review of 2833 post-acute patient outcomes per immune dysregulation and microbial translocation in long COVID

A significant number of persons with coronavirus disease 2019 (COVID-19) experience persistent, recurrent, or new symptoms several months after the acute stage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This phenomenon, termed post-acute sequelae of SARS-CoV-2 (PASC) or long COVID, is associated with high viral titers during acute infection, a persistently hyperactivated immune system, tissue injury by NETosis-induced micro-thrombofibrosis (NETinjury), microbial translocation, complement deposition, fibrotic macrophages, the presence of autoantibodies, and lymphopenic immune environments. Here, we review the current literature on the immunological imbalances that occur during PASC. Specifically, we focus on data supporting common immunopathogenesis and tissue injury mechanisms shared across this highly heterogenous disorder, including NETosis, coagulopathy, and fibrosis. Mechanisms include changes in leukocyte subsets/functions, fibroblast activation, cytokine imbalances, lower cortisol, autoantibodies, co-pathogen reactivation, and residual immune activation driven by persistent viral antigens and/or microbial translocation. Taken together, we develop the premise that SARS-CoV-2 infection results in PASC as a consequence of acute and/or persistent single or multiple organ injury mediated by PASC determinants to include the degree of host responses (inflammation, NETinjury), residual viral antigen (persistent antigen), and exogenous factors (microbial translocation). Determinants of PASC may be amplified by comorbidities, age, and sex.

Assessment of sST2 Behaviors to Evaluate Severity/Clinical Impact of Acute Pulmonary Embolism

Pulmonary embolism (PE) is a potentially life-threatening disorder. Beyond its usefulness in the prognostic stratification of heart failure, sST2 can represent a biomarker with high utility in several acute conditions. Our study was aimed to investigate whether sST2 can be used as a clinical marker of severity and prognostic outcome in acute PE. We enrolled 72 patients with documented PE and 38 healthy subjects; we measured the plasma concentrations of sST2 to evaluate the prognostic and severity performance of different levels of sST2 according to its association with the pulmonary embolism severity index (PESI) score and several parameters of respiratory function. PE patients had significantly higher levels of sST2 compared with healthy subjects (87.74 ± 17.1 vs. 17.1 ± 0.4 ng/mL, p < 0.001); we found higher PESI scores and serum lactate values in the group of patients with sST2 > 35 ng/mL compared with patients with sST2 < 35 ng/mL (138.7 ± 14.9 vs. 103.7 ± 15.1 and 2.43 ± 0.69 vs. 1.025 ± 0.05 mmol/L, respectively; p < 0.05). Patients with sST2 > 35 ng/mL showed higher radiological severity of PE compared with patients with sST2 < 35 ng/mL. Moreover, sST2 was the strongest parameter with a discriminative capacity for the development of acute respiratory failure and a PESI score >106 with respect to C reactive protein (CRP), creatinine, d-dimer, and serum lactate. We clearly demonstrated that sST2 significantly increased in PE and that its elevation was associated with disease severity. Therefore, sST2 may be used as a clinical marker in the evaluation of PE severity. However, further studies with larger patient populations are required to confirm these findings.

Acute Cardiorenal Syndrome: Epidemiology, Pathophysiology, Assessment, and Treatment

Acute cardiorenal syndrome (CRS) is often observed in patients with acute kidney injury (AKI) in the cardiac intensive care unit and is reported to be associated with poor prognosis. Volume disorder or re-distribution, renin-angiotensin-aldosterone system activation, and neurohormonal and sympathetic nervous system activation have been suggested to be related to the occurrence of acute CRS. There is a lack of biomarkers that can identify changes in renal function in patients with acute CRS. Evidence-based medications are limited in the management of acute CRS in AKI. Therefore, we reviewed the epidemiology, pathophysiology, clinical assessment, and treatment of acute CRS in AKI.

Full-length IL-33 augments pulmonary fibrosis in an ST2- and Th2-independent, non-transcriptomic fashion

Mature IL-33 (MIL33) acting through its receptor, ST2, is known to regulate fibrosis. The precursor, full-length IL-33 (FLIL33), may function differently from MIL33 and independently of ST2. Here we report that genetic deletion of either IL-33 or ST2 attenuates pulmonary fibrosis in the bleomycin model, as does Cre-induced IL-33 deficiency in response to either acute or chronic bleomycin challenge. However, adenovirus-mediated gene delivery of FLIL33, but not MIL33, to the lungs of either wild-type or ST2-deficient mice potentiates the profibrotic effect of bleomycin without inducing a Th2 phenotype. In cultured mouse lung cells, FLIL33 overexpression induces moderate and distinct transcriptomic changes compared with a robust response induced by MIL33, whereas ST2 deletion abrogates the effects of both IL-33 forms. Thus, FLIL33 may contribute to fibrosis in an ST2-independent, Th2-independent, non-transcriptomic fashion, suggesting that pharmacological targeting of both FLIL33 and MIL33 may prove efficacious in patients with pulmonary fibrosis.

Therapeutic Perspectives of IL1 Family Members in Liver Diseases: An Update

Interleukin (IL) 1 superfamily members are a cornerstone of a variety of inflammatory processes occurring in various organs including the liver. Progression of acute and chronic liver diseases regardless of etiology depends on the stage of hepatocyte damage, the release of inflammatory cytokines and disturbances in gut microbiota. IL1 cytokines and receptors can have pro- or anti-inflammatory roles, even dual functionalities conditioned by the microenvironment. Developing novel therapeutic strategies to block the IL1/IL1R signaling pathways seems like a reasonable option. This mode of action is now exploited by anakinra and canakinumab, which are used to treat different inflammatory illnesses, and studies in liver diseases are on the way. In this mini review, we have focused on the IL1 superfamily members, given their crucial role in liver inflammation diseases, specifically discussing their potential role in developing new treatment strategies.

Allies or enemies? The effect of regulatory T cells and related T lymphocytes on the profibrotic environment in bleomycin-injured lung mouse models

Idiopathic pulmonary fibrosis (IPF) is characterized by permanent scarring of lung tissue and declining lung function, and is an incurable disease with increase in prevalence over the past decade. The current consensus is that aberrant wound healing following repeated injuries to the pulmonary epithelium is the most probable cause of IPF, with various immune inflammatory pathways having been reported to impact disease pathogenesis. While the role of immune cells, specifically T lymphocytes and regulatory T cells (Treg), in IPF pathogenesis has been reported and discussed recently, the pathogenic or beneficial roles of these cells in inducing or preventing lung fibrosis is still debated. This lack of understanding could be due in part to the difficulty in obtaining diseased human lung tissue for research purposes. For this reason, many animal models have been developed over the years to attempt to mimic the main clinical hallmarks of IPF: among these, inducing lung injury in rodents with the anti-cancer agent bleomycin has now become the most commonly studied animal model of IPF. Pulmonary fibrosis is the major side effect when bleomycin is administered for cancer treatment in human patients, and a similar effect can be observed after intra-tracheal administration of bleomycin to rodents. Despite many pathophysiological pathways of lung fibrosis having been investigated in bleomycin-injured animal models, one central facet still remains controversial, namely the involvement of specific T lymphocyte subsets, and in particular Treg, in disease pathogenesis. This review aims to summarize the major findings and conclusions regarding the involvement of immune cells and their receptors in the pathogenesis of IPF, and to elaborate on important parallels between animal models and the human disease. A more detailed understanding of the role of Treg and other immune cell subsets in lung injury and fibrosis derived from animal models is a critical basis for translating this knowledge to the development of new immune-based therapies for the treatment of human IPF.

ST2 and CSF-1 as potential druggable targets of inflammatory bowel diseases: Results from two-sample Mendelian randomization study

Novel druggable targets are warranted for inflammatory bowel disease (IBD) treatment. We aimed to identify novel circulating proteins with causal associations with the risk of IBDs and provide potential therapeutic targets for IBD treatment. We performed a two-sample Mendelian randomization (MR) study to explore the associations of 55 circulating biomarkers on the risk of IBD, Crohn's disease (CD), and ulcerative colitis (UC) by leveraging the summary statistics from large genomewide association studies and protein quantitative trait loci studies. The individual estimate was pooled together by meta-analyses to estimate the causal effects of each outcome. In univariable MR, we identified several circulating proteins showed potential correlation with IBD, UC, and CD. Of note, we observed that a genetically proxied increased level of suppression of tumorigenicity 2 (ST2) was associated with an elevated risk of IBD (odds ratios [ORs] 1.133, 95% confidence interval [CI] 1.091-1.176, p < 0.0001), CD (ORs 1.188, 95% CI 1.103-1.281, p < 0.0001), and UC cohorts (ORs 1.087, 95% CI 1.050-1.125, p < 0.0001). Additionally, we observed a consistent positive correlation between the level of CSF-1 and the increased risk of IBD in individual MR, with statistically significant causal associations in the meta-analyses with ORs equal to 1.217 (IBD, 95% CI 1.115-1.328, p < 0.0001), 1.223 (CD, 95% CI 1.082-1.382, p = 0.0013), and 1.179 (UC, 95% CI 1.055-1.317, p = 0.0037). This study provided evidence for potential casual associations between circulating ST2 and CSF-1 levels, and increased risks of IBD, UC, and CD, implicating potential treatment targets for IBD and subtypes.

Interleukin-33 Derived from Endometriotic Lesions Promotes Fibrogenesis through Inducing the Production of Profibrotic Cytokines by Regulatory T Cells

In endometriosis, it has been widely believed that the local immunological milieu is Th2-skewed. Regulatory T cells (Tregs) promote fibrogenesis of endometriosis through the transforming growth factor β1 (TGF-β1) and platelet-derived growth factor (PDGF) signaling pathways. We aimed to explore whether Tregs in endometriotic lesions acquire increased production of effector cytokines under the influence of lesion-derived interleukin (IL)-33. We extracted lymphocytes from normal endometrium and ovarian endometrioma to evaluate the expression of IL-4, IL-13, interferon-γ (IFN-γ), TGF-β1, and the IL-33 receptor (ST2) by Tregs from these tissues. Colocalization of IL-33 and FOXP3 in normal endometrium and ovarian endometrioma was evaluated by immunofluorescence. Tregs and endometriotic stromal cells were co-cultured and treated with anti-IL-33 antibody, and the cytokines produced by Tregs were analyzed by flow cytometry and enzyme-linked immunosorbent assay (ELISA). Tregs in ovarian endometrioma produced significant amounts of IL-4, IL-13, TGF-β1, and ST2. Colocalization of IL-33 and FOXP3 was detected in ovarian endometrioma. IL-33 from endometriotic stromal cells caused the differentiation of lesional Tregs into type 2 T helper (Th2)-like cells, along with increased production of TGF-β1 by Tregs. Thus, Tregs and endometriotic lesions engage active crosstalk through IL-33 to promote fibrogenesis in endometriosis, and, as such, this finding opens up new avenues to identify novel therapeutic targets for endometriosis.