The Role of Interleukin-33 as an Inflammatory Marker in Differential Diagnosis of Idiopathic Granulomatous Mastitis and Breast Cancer

Novel insights: crosstalk with non-puerperal mastitis and immunity

The two primary types of non-puerperal mastitis (NPM) are granulomatous lobular mastitis (GLM) and plasma cell mastitis (PCM). Existing research indicates that immune inflammatory response is considered to be the core of the pathogenesis of GLM and PCM, and both innate and adaptive immune responses play an important role in the pathophysiology of PCM and GLM. However, the regulatory balance between various immune cells in these diseases is still unclear. Consequently, we present a comprehensive summary of the immune-related variables and recent advances in GLM and PCM.

Evaluation of significantly changed chemokine factors of idiopathic granulomatous mastitis in non-puerperal patients

Idiopathic granulomatous mastitis (IGM), a recurrent inflammation disease of the non-lactating breast, has had an increasing clinical morbidity rate in recent years, and its complicated symptoms and unclear etiology make it challenging to treat. This rare benign inflammatory breast disease, centered on the lobules, represents the most challenging type of non-puerperal mastitis (NPM), also known as non-lactating mastitis. In this study, patients diagnosed with IGM (M, n = 23) were recruited as cases, and patients with benign control breast disease (C, n = 17) were enrolled as controls. Cytokine microarray detection measured and analyzed the differentially expressed cytokine factors between IGM and control patients. Then, we verified the mRNA and protein expression levels of the significantly changed cytokine factors using Q-RT-PCR, ELISA, western blot, and IHC experiments. The cytokine factor expression levels significantly changed compared to the control group. We observed a significant increase between IGM and control patients in cytokine factors expression, such as interleukin-1β (IL-1β), monokine induced by gamma interferon (MIG), macrophage inflammatory protein (MIP)-1α, MIP-1β, tumor necrosis factor receptor 2 (TNF RII). Then, we verified the expression of these top five dysregulated factors in both mRNA and protein levels. Our results demonstrated the cytokine map in IGM and indicated that several cytokines, especially chemokines, were associated with and significantly dysregulated in IGM tissues compared to the control group. The chemokine factors involved might be essential in developing and treating IGM. These findings would be helpful for a better understanding of IGM and offer valuable insights for devising novel diagnostic and therapeutic strategies.

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.

Immune pathogenesis of idiopathic granulomatous mastitis: from etiology toward therapeutic approaches

Idiopathic granulomatous mastitis (IGM) is a noncancerous, chronic inflammatory disorder of breast with unknown causes, posing significant challenges to the quality of life due to its high refractoriness and local aggressiveness. The typical symptoms of this disease involve skin redness, a firm and tender breast mass and mastalgia; others may include swelling, fistula, abscess (often without fever), nipple retraction, and peau d'orange appearance. IGM often mimics breast abscesses or malignancies, particularly inflammatory breast cancer, and is characterized by absent standardized treatment options, inconsistent patient response and unknown mechanism. Definite diagnosis of this disease relies on core needle biopsy and histopathological examination. The prevailing etiological theory suggests that IGM is an autoimmune disease, as some patients respond well to steroid treatment. Additionally, the presence of concurrent erythema nodosum or other autoimmune conditions supports the autoimmune nature of the disease. Based on current knowledge, this review aims to elucidate the autoimmune-favored features of IGM and explore its potential etiologies. Furthermore, we discuss the immune-mediated pathogenesis of IGM using existing research and propose immunotherapeutic strategies for managing this condition.

Decoding the IL-33/ST2 Axis: Its Impact on the Immune Landscape of Breast Cancer

Interleukin-33 (IL-33) has emerged as a critical cytokine in the regulation of the immune system, showing a pivotal role in the pathogenesis of various diseases including cancer. This review emphasizes the role of the IL-33/ST2 axis in breast cancer biology, its contribution to cancer progression and metastasis, its influence on the tumor microenvironment and cancer metabolism, and its potential as a therapeutic target. The IL-33/ST2 axis has been shown to have extensive pro-tumorigenic features in breast cancer, starting from tumor tissue proliferation and differentiation to modulating both cancer cells and anti-tumor immune response. It has also been linked to the resistance of cancer cells to conventional therapeutics. However, the role of IL-33 in cancer therapy remains controversial due to the conflicting effects of IL-33 in tumorigenesis and anti-tumor response. The possibility of targeting the IL-33/ST2 axis in tumor immunotherapy, or as an adjuvant in immune checkpoint blockade therapy, is discussed.

Clinical, microbiological, immunological and hormonal profiles of patients with granulomatous mastitis

Various studies on the etiology and other aspects of granulomatous mastitis (GM) have been performed; however, a lot of controversies have arisen. The present study aimed to present the clinicopathological findings and identify the sensitivity and resistance of isolated bacteria in patients with GM. In this cross-sectional study 63 female patients with a confirmed histopathological diagnosis of GM were included. A core needle biopsy was conducted for the patients to obtain a sample for histopathological examination and bacterial culture. In total, 46 types of antibiotics were used to determine the sensitivity and resistance of each isolated bacterial species. All the medical and clinical records of the patients were acquired through the completion of a questionnaire form in person or, if necessary, through the evaluation of their medical records in the database of the relevant center. The majority of the patients were in the premenopausal or perimenopausal period. GM was unilateral in 58.7% of the patients. The most common symptom was pain, followed by fever and chills. The mean ranges of the erythrocyte sedimentation rate, C-reactive protein, IL-6, IL-17, C5a, white blood count, neutrophil-to-lymphocyte ratio, and prolactin tests were significantly elevated in comparison to the normal ranges. In total, nine different bacterial species were isolated from the bacterial culture of the core biopsy samples, and 50% of the isolated bacterial species were sensitive to trimethoprim-sulfamethoxazole. Since there is no consensus on the etiology of GM, any additional studies related to this aspect expand the current understanding of this puzzling condition.

A Case of a Female Patient Presenting With Idiopathic Granulomatous Mastitis With Superimposed Enterococcus Avium Infection

Idiopathic granulomatous mastitis (IGM) is defined as an uncommon, benign, chronic inflammatory disease of unknown etiology that affects the breast and can mimic breast cancer. It usually manifests as a solid, ill-defined breast lump in postpartum women of reproductive age. Furthermore, because it lacks a particular radiographic finding, core biopsy and histology are the only ways to make a conclusive diagnosis. There is no agreement on the best way to treat IGM. Ideally, a multidisciplinary approach should be used to weigh the benefits and drawbacks of each treatment option, with options such as observation, antibiotics, surgery, and medication therapy being examined (steroids and immunosuppressants). In this report, we review a case of a patient who had IGM with superimposed Enterococcus avium infection. To our knowledge, such a report is considered unprecedented in the Middle East. A literature review on IGM will be presented, as well as the clinical presentation, association with bacterial infection, treatment, and pathological and radiographic findings.

Tissue proteome analysis revealed an association between cancer, immune system response, and the idiopathic granulomatous mastitis

Idiopathic Granulomatous Mastitis (IGM) is a disease that clinically mimics breast cancers with symptoms of pain, edema, erythema, nipple discharge, nipple retraction, and fistula. Although IGM is considered to be formed by autoimmune responses or infections, the molecular mechanism behind formation and progress is unknown. Therefore, in this study, we aimed to investigate molecular mechanisms underlying IGM formation, progress, and recurrence by monitoring the changes at the proteome level. Protein extracts prepared from IGM (n = 15) and within-control tissues (n = 15) were subjected to nHPLC followed by LC-MS/MS proteomic analysis. Label-free quantitation analysis revealed that sixty differentially regulated between the two groups. Those proteins were classified based on their role in metabolic pathways using bioinformatics tools. Based on DAVID analysis, 16 of the differently regulated proteins were associated with the immune system, while 17 proteins were involved in cancer metabolism. STRING analysis showed that five of the differentially regulated proteins were associated with combined immune deficiency which were PNP, TAP1, ITGAL, PRKDC, and PTPRC while the other proteins were involved in insulin response and neutrophil degranulation. This study is one of the very few studies that investigated the changes in protein expressions of IGM tissues compared to controls. For the first time, we have shown the relationship of IGM with the immune system at the protein level and also underlined the cancer-like behavior of the disease. Furthermore, the proteins that were pointed out as combined immune deficiency-related proteins may have value as diagnostic markers for idiopathic granulomatous mastitis although further studies are needed to shed more light on the pathogenesis of the disease.

Benign or premalignant? Idiopathic granulomatous mastitis later diagnosed as ductal carcinoma breast cancer: Case report and review of literature

Idiopathic granulomatous mastitis (IGM) is a rare benign infectious disease of the breast, commonly presenting with a unilateral breast mass. Since GM's clinical presentation and imaging can be very similar to breast cancer, diagnosing GM can be challenging. So far, various reports have demonstrated the probable correlation and co-occurrence of granulomatous mastitis and breast cancer. This report presents a 38-year-old female with invasive ductal carcinoma, previously diagnosed as IGM.

Concurrent granulomatous mastitis and invasive ductal cancer in contralateral breasts-a case report and review

Idiopathic granulomatous mastitis (GM) is an uncommon chronic benign disease of the breast that is challenging to clinically distinguish from malignancy. However, it is unusual to diagnose GM concurrently with carcinoma in the same breast and rarer still to encounter GM and malignancy in contralateral breasts. We describe the case of a 39-year-old female who presented with right multifocal breast cancer and left granulomatous mastitis, discuss complexities in her management plan and review the literature on this unusual concurrent condition.

New Findings on Autoimmune Etiology of Idiopathic Granulomatous Mastitis: Serum IL-17, IL-22 and IL-23 Levels of Patients

BACKGROUND

Idiopathic Granulomatous Mastitis (IGM) is a benign chronic inflammatory breast disease that mimics breast cancer, and the etiopathogenesis has not yet been fully evaluated. Autoimmunity has received the most focus as a possible etiology. Our aim in this prospective clinical study was to investigate the possible association between the cytokines, interleukin IL-17, IL-22, IL-23 and IGM.

MATERIALS AND METHODS

The current study was conducted in 26 women with histopathologically diagnosed IGM, and 15 control women of reproductive age having no breast disease history. Blood samples were collected, and serum concentrations of IL-17, IL-22, and IL-23 were determined.

RESULTS

In the analysis of variables, the patients with IGM and the control group had statistically significant differences between serum IL-22 titers (p = 0.0378) and IL-23 titers (p = 0.0469. No statistically significant difference was found between IGM patients and the control group in serum IL-17 titers (p = 0.9724).

CONCLUSION

The results of the current study, especially pertaining to serum IL-22 and IL-23 levels, support the etiopathogenesis of IGM in favor of the autoinflammatory thesis. Nevertheless, this thesis should be supported by a large case number and prospective clinical studies.

Preoperative Fibrinogen and Hematological Indexes in the Differential Diagnosis of Idiopathic Granulomatous Mastitis and Breast Cancer

Background and Aim: Studies on hematological parameters in the differential diagnosis of idiopathic granulomatous mastitis (IGM) and breast cancer (BC) are limited. This study investigated whether preoperative fibrinogen and hematological indexes can be used in the differential diagnosis of patients with IGM and early-onset BC. Methods: Fifty patients with BC, 55 patients with IGM, and 50 healthy volunteer women were included in the study. Results: There was a statistically significant difference between the IGM and the BC with respect to fibrinogen, fibrinogen/albumin (Fib/Alb) ratio, C-reactive protein (CRP), white blood cells (WBC), neutrophils, neutrophil–lymphocyte ratio (NLR), platelet–lymphocyte ratio (PLR), and monocyte values. When fibrinogen (p < 0.001), the Fib/Alb ratio (p < 0.001), CRP (p < 0.001), WBC (p < 0.001), neutrophil (p < 0.001), NLR (p < 0.001), monocyte (p = 0.008), and 2-hour sedimentation rate (p < 0.001) were compared between the groups, the highest levels were found in the IGM group. There was a negative relationship between CRP and albumin, and a positive relationship was observed between CRP and WBC, NLR, PLR, and 2-h sedimentation rate. CRP had the highest sensitivity (95%), whereas the Fib/Alb ratio (86%) had the highest specificity. Patients with recurrent IGM had increased fibrinogen, Fib/Alb, CRP, neutrophils, NLR, and 2-h erythrocyte sedimentation rate (ESR) and decreased lymphocyte levels compared to non-recurrent patients. Conclusions: Preoperative CRP, albumin, fibrinogen, Fib/Alb, WBC, neutrophil, NLR, monocyte, and 2-h ESR have considerable potential to be early and sensitive biomarkers of IGM caused by inflammation compared to BC. These parameters also have a significant effect on the recurrence of the disease, suggesting their potential as a practical guide for the differential diagnosis of BC from IGM.

Serum C-Reactive Protein and Interleukin-6 Levels as Biomarkers for Disease Severity and Clinical Outcomes in Patients with Idiopathic Granulomatous Mastitis

Idiopathic granulomatous mastitis (IGM) is a rare inflammatory breast disease mimicking breast cancer. Limited research has been conducted on the application of serum biomarkers. This study aims to investigate the association of serum biomarkers with disease severity in patients with IGM. From November 2011 to March 2020, medical records of patients with IGM were reviewed. Serum cytokine levels were measured in patients and healthy controls between July 2018 and March 2020. A total of 41 patients with histologically proven IGM were found. Serum interleukin (IL)-6 level was significantly higher in patients with IGM (n = 11) than healthy controls (n = 7). Serum IL-6 and C-reactive protein (CRP) levels were significantly higher in patients with severe disease than mild and moderate disease. Serum IL-6 (Spearman’s ρ = 0.855; p < 0.001) and CRP (Spearman’s ρ = 0.838; p = 0.001) levels were associated with time to resolution. A higher serum CRP level was associated with a longer time to resolution (B = 0.322; p < 0.001) in multiple linear regression analysis. Serum IL-6 and CRP levels can be used as biomarkers for the evaluation of disease severity in IGM. IL-6 may play a crucial role in the immunopathology of IGM.

PD-1 blockade combined with IL-33 enhances the antitumor immune response in a type-1 lymphocyte-mediated manner

PD-1 immune checkpoint blockade and cytokine IL-33 have shown significant therapeutic effects in tumor immunotherapy. These therapies promote CD8⁺ T cell activation, proliferation, and effector functions. However, there were few research about the combined therapy efficacy. In this study, we established B16-empty vector and B16-IL33 melanoma mouse models and treated with PD-1 monoclonal antibody. We reported that PD-1 blockade combined with cytokine IL-33 further inhibited tumor progression and prolonged the survival of tumor-bearing mice. Mechanistically, the combination therapy was found to further facilitate CD4⁺ and CD8⁺ T lymphocytes accumulation, and enhance the antitumor effects of CD4⁺or CD8⁺tumor-infiltrating lymphocytes by promoting type-1 immune response within the tumor microenvironment using flow cytometry and quantitative real time polymerase chain reaction. Thus, PD-1 blockade combined with IL-33 has application potential in tumor immunotherapy. Further, this study provides a new promising strategy and theoretical basis for tumor combination immunotherapy.

Idiopathic Granulomatous Mastitis: Etiology, Clinical Manifestation, Diagnosis and Treatment

Idiopathic granulomatous mastitis (IGM) is a rare form of chronic inflammatory breast disease. Although it is a benign breast lesion, it may be sometimes difficult to distinguish from breast cancer. The cause of IGM is unknown, but may be associated with autoimmunity, abnormal hormone levels and infection. While the clinical manifestations of IGM involve various manifestations of inflammation, the diagnosis is principally established by histopathology, characterized by non-caseating granulomas and microabscess formation centered on the breast lobules. Therapeutic options for IGM range from observation to various medical treatments, such as steroids, immunosuppressants, and antibiotics, to surgical intervention, particularly if secondarily infected. Given that the controversy on etiology and treatment choices, we accomplished the present review through reviewing IGM-related literature published in 'Pubmed' and 'Web of science' databases during 1997 to 2020, aiming to provide the basis for rational clinical diagnosis and treatment.

Higher Dietary Inflammatory Index Scores are Associated with Increased Odds of Benign Breast Diseases in a Case-Control Study

Purpose

Dietary inflammatory index (DII) is a new tool for assessing the inflammatory potential of diet. Since there is no study that has investigated the association of DII and benign breast diseases (BBD), the aim of our study was to compare DII scores in patients with and without BBD.

Methods

One hundred and eleven (111) subjects with BBD and 104 healthy women attending the Iranian Center for Breast Cancer affiliated with the Academic Center for Education, Culture and Research were enrolled in a case–control study. Dietary data collected using a 168‑item validated food frequency questionnaire (FFQ). Energy-adjusted DII was calculated based on FFQ. Socio demographic data were collected by interview. In addition, physical activity was measured by the International Physical Activity Questionnaire (IPAQ). Weight, height and waist circumference were also measured.

Results

After adjustment for multiple confounding variables, participants at the highest tertile of DII had increased OR for BBD (OR=1.7, 95% CI=0.75–3.95) (P-trend =0.04).

Conclusion

The increased chance of BBD was suggested with a higher consumption of diets with inflammatory potential. However, this result should be interpreted with caution as OR was not statistically significant. Interventional studies are warranted to elucidate the role of inflammatory diets in the development of BBD.

The clinical value of interleukins-8, -10, and -17 in idiopathic granulomatous mastitis

INTRODUCTION

Idiopathic granulomatous mastitis (IGM) is a rare, chronic inflammatory benign breast disease. Although the etiology of this disease is unknown, it has been suggested that hormonal disorders, autoimmunity, smoking, and α1-antitrypsin deficiency may play a role in the etiopathogenesis. The aim is to investigate the changes in cytokine profiles including interleukin (IL)-4, -8, -10, -17, and tumor necrosis factor (TNF)-alpha in patients with IGM.

METHODS

Forty-seven patients with pathologically diagnosed IGM and 30 healthy women were included. The cytokines including IL-4, -8, 10, -17, and TNF-alpha were measured by human enzyme-linked immunosorbent assay.

RESULTS

The IL-8, IL-10, and IL-17 levels were higher in IGM patients than control group (p = .002; p = .008; and p = .018, respectively). The IL-8 levels of patients with active lesions and in remission were statistically higher than the control group (p = .027 and p = .015, respectively). IL-10 levels of patients in remission were higher than the control group (p = .024). There was no difference in IL-4 and TNF-ɑ levels between all groups.

CONCLUSION

These results showed that proinflammatory cytokines including IL-8 and IL-17 have role in pathogenesis of IGM. However, the increased levels of IL-10 in especially patients in remission suggest that it reduces the release of proinflamatory cytokines as well as suppressing their function and activation for controlling IGM. Although IGM is thought to be a surgical disease, these cytokine changes indicate the presence of serious immune dysregulation. This suggests that in the treatment of IGM, treatment needs to evolve from surgery to medical treatment.Key points• The IL-8, IL-10, and IL-17 levels were higher in IGM patients than in control group.• The IL-8 levels of both patients with active lesions and in remission were high.• There was no difference in IL-4 and TNF-ɑ levels between all groups.

Tissue Cytokine IL-33 Modulates the Cytotoxic CD8 T Lymphocyte Activity During Nutrient Deprivation by Regulation of Lineage-Specific Differentiation Programs

IL-1 family member IL-33 exerts a variety of immune activating and regulating properties and has recently been proposed as a prognostic biomarker for cancer diseases, although its precise role in tumor immunity is unclear. Here we analyzed in vitro conditions influencing the function of IL-33 as an alarmin and a co-factor for the activity of cytotoxic CD8+ T cells in order to explain the widely discussed promiscuous behavior of IL-33 in vivo. Circulating IL-33 detected in the serum of healthy human volunteers was biologically inactive. Additionally, bioactivity of exogenous recombinant IL-33 was significantly reduced in plasma, suggesting local effects of IL-33, and inactivation in blood. Limited availability of nutrients in tissue causes necrosis and thus favors release of IL-33, which-as described before-leads to a locally high expression of the cytokine. The harsh conditions however influence T cell fitness and their responsiveness to stimuli. Nutrient deprivation and pharmacological inhibition of mTOR mediated a distinctive phenotype characterized by expression of IL-33 receptor ST2L on isolated CD8+ T cells, downregulation of CD8, a transitional CD45RAlowROlow phenotype and high expression of secondary lymphoid organ chemokine receptor CCR7. Under nutrient deprivation, IL-33 inhibited an IL-12 induced increase in granzyme B protein expression and increased expression of GATA3 and FOXP3 mRNA. IL-33 enhanced the TCR-dependent activation of CD8+ T cells and co-stimulated the IL-12/TCR-dependent expression of IFNγ. Respectively, GATA3 and FOXP3 mRNA were not regulated during TCR-dependent activation. TCR-dependent stimulation of PBMC, but not LPS, initiated mRNA expression of soluble IL-33 decoy receptor sST2, a control mechanism limiting IL-33 bioactivity to avoid uncontrolled inflammation. Our findings contribute to the understanding of the compartment-specific activity of IL-33. Furthermore, we newly describe conditions, which promote an IL-33-dependent induction of pro- or anti-inflammatory activity in CD8+ T cells during nutrient deprivation.

Systemic Inflammation Score as a Novel Prognostic Indicator for Patients Undergoing Video-Assisted Thoracoscopic Surgery Lobectomy for Non-Small-Cell Lung Cancer

BACKGROUND

To evaluate the prognostic significance of systemic inflammation score (SIS) for patients undergoing video-assisted thoracoscopic surgery (VATS) lobectomy for non-small-cell lung cancers (NSCLCs). Methods: This retrospective cohort study was conducted on the prospectively maintained database in our institution during the study period. Preoperative SIS comprising serum albumin (sALB) and lymphocyte-to-monocyte ratio (LMR) was graded into 0, 1 and 2. Survival analysis was performed to distinguish differences in postoperative survival between three groups of SIS. Finally, multivariate Cox proportional hazards regression analyses were conducted to determine independent prognostic factors. Results: There were 390 patients with operable NSCLCs included. We applied sALB at 40 g/L and our median LMR at 3.91 as the cutoffs for modified SIS scoring criteria. Both overall survival (OS) and disease-free survival (DFS) were significantly shortened in a step-wise fashion with each 1-point increase in SIS (Log-rank p < .001). There was a significant step-wise decline in both OS and DFS rates in proportion to SIS (p < .001). No difference was found in postoperative complications between three groups of SIS. Multivariate analyses finally demonstrated that both SIS = 1 and SIS = 2 could be independent prognostic factors for unfavorable OS and DFS of NSCLCs. Conclusions: SIS can serve as a novel risk stratification tool to refine the prognostic prediction for surgical NSCLCs.

Idiopathic Granulomatous Mastitis Presenting as a Breast Pseudotumor: Case Reports with Review of the Literature

Idiopathic granulomatous mastitis is a rare benign inflammatory breast disease that affects women of childbearing age with a history of breastfeeding. It usually presents as an enlarging breast mass that can greatly mimic breast cancer. Moreover, it does not have a specific radiographic finding, so the only way to reach a definitive diagnosis is by core biopsy and histology. Furthermore, a consensus regarding the best treatment modality has not been reached yet. In this report, we describe the cases of two patients who suffered from this disease, and to our knowledge, such a report is the first of its kind to address this topic in this region. Therefore, because of its uncommon nature and obscure presentation, we hereby report two cases of idiopathic granulomatous mastitis. The clinical presentation, treatment, and pathological findings are described, and a literature review on idiopathic granulomatous mastitis will be reported.

The Role of IL-33/ST2 Pathway in Tumorigenesis

Cancer is initiated by mutations in critical regulatory genes; however, its progression to malignancy is aided by non-neoplastic cells and molecules that create a permissive environment known as the tumor stroma or microenvironment (TME). Interleukin 33 (IL-33) is a dual function cytokine that also acts as a nuclear factor. IL-33 typically resides in the nucleus of the cells where it is expressed. However, upon tissue damage, necrosis, or injury, it is quickly released into extracellular space where it binds to its cognate receptor suppression of tumorigenicity 2 (ST2)L found on the membrane of target cells to potently activate a T Helper 2 (Th2) immune response, thus, it is classified as an alarmin. While its role in immunity and immune-related disorders has been extensively studied, its role in tumorigenesis is only beginning to be elucidated and has revealed opposing roles in tumor development. The IL-33/ST2 axis is emerging as a potent modulator of the TME. By recruiting a cohort of immune cells, it can remodel the TME to promote malignancy or impose tumor regression. Here, we review its multiple functions in various cancers to better understand its potential as a therapeutic target to block tumor progression or as adjuvant therapy to enhance the efficacy of anticancer immunotherapies.