Cytokines are soluble factors that play vital roles in systemic function due to their ability to initiate and mediate cell-to-cell communication. Another important mechanism of intercellular communication that has gained significant attention in the past 10 years is the release of extracellular vesicles (EVs). EVs are released by all cells during normal physiology, in states of resting and activation, as well as during disease. Accumulating evidence indicates that cytokines may be packaged into EVs, and the packaging of cytokines into EVs, along with their ultimate secretion, may also be regulated by cytokines. Importantly, the repertoire of biomolecules packaged into EVs is shaped by the biological state of the cell (resting vs. activated and healthy vs. disease) and the EV biogenesis pathway involved, thus providing mechanisms by which EV packaging and secretion may be modulated. Given the critical role of cytokines in driving acute and chronic inflammatory and autoimmune diseases, as well as their role in establishing the tumor immune microenvironment, in this review, we will focus on these disease settings and summarize recent progress and mechanisms by which cytokines may be packaged within and modulated by EVs, as a therapeutic option for regulating innate and adaptive immunity.

Background and study aims The COVID-19 pandemic has disrupted routine medical care due to uncertainty regarding the risk of viral spread. One major concern for viral transmission to both patients and providers is performing aerosol-generating procedures such as endoscopy. As such, we performed a prospective study to examine the extent of viral contamination present in the local environment before and after endoscopic procedures on COVID-19 positive patients. Materials and methods A total of 82 samples were collected from 23 surfaces in the procedure area of four COVID-positive patients undergoing upper endoscopic procedures. Samples were collected both before and after the procedure. severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA was extracted and quantified using reverse transcription quantitative polymerase chain reaction with primers to detect nucleocapsid RNA, and results reported as the number of viral copies per square centimeter of contaminated surface. Results A total of six positive samples were detected from three of the four patients. The floor beneath the patient bed was the most common site of viral RNA, but RNA was also detected on the ventilator monitor prior to the procedure and the endoscope after the procedure. Conclusions The risk of SARS-CoV-2 transmission associated with upper endoscopy procedures is low based on the low rate of surface contamination. Some surfaces in close proximity to the patient and endoscopist may pose a higher risk for contamination. Patient positioning and oxygen delivery methods may influence the directionality and extent of viral spread. Our results support the use of appropriate personal protection to minimize risk of viral transmission.

BackgroundCancer-testis (CT) genes are targets for tumor antigen-specific immunotherapy given that their expression is normally restricted to the immune-privileged testis in healthy individuals with aberrant expression in tumor tissues. While they represent targetable germ-tissue antigens and play important functional roles in tumorigenesis, there is currently no standardized approach for identifying clinically relevant CT genes. Optimized algorithms and validated methods for accurate prediction of reliable CT antigens with high immunogenicity are also lacking.MethodsSequencing data from the Genotype-Tissue Expression (GTEx) and The Genomic Data Commons (GDC) databases was utilized for the development of a bioinformatic pipeline to identify CT exclusive genes. A CT germness score was calculated based on the number of CT genes expressed within a tumor type and their degree of expression. The impact of tumor germness with clinical outcome was evaluated using healthy GTEx and GDC tumor samples. We then used a triple-negative breast cancer mouse model to develop and test an algorithm that predicts epitope immunogenicity based on the identification of germline sequences with strong MHCI and MHCII binding affinities. Germline sequences for CT genes were synthesized as long synthetic peptide vaccines and tested in the 4T1 triple-negative model of invasive breast cancer with Poly(I:C) adjuvant. Vaccine immunogenicity was determined by flow cytometric analysis ofin vitroandin vivoT cell responses. Primary tumor growth and lung metastasis was evaluated by histopathology, flow cytometry and colony formation assay.ResultsWe developed a new bioinformatic pipeline to reliably identify CT exclusive genes as immunogenic targets for immunotherapy. We identified CT genes that are exclusively expressed within the testis, lack detectable thymic expression, and are significantly expressed in multiple tumor types. High tumor germness correlated with tumor progression but not with tumor mutation burden, supporting CT antigens as appealing targets in low mutation burden tumors. Importantly, tumor germness also correlated with markers of anti-tumor immunity. Vaccination of 4T1 tumor bearing mice with Siglece and Lin28a antigens resulted in increased T cell anti-tumor immunity and reduced primary tumor growth and lung metastases.ConclusionOur results present a novel strategy for the identification of highly immunogenic CT antigens for the development of targeted vaccines that induce anti-tumor immunity and inhibit metastasis.

Despite the progress made in identifying cellular factors and mechanisms that predict progression and metastasis, breast cancer remains the second leading cause of death for women in the US. Using The Cancer Genome Atlas and mouse models of spontaneous and invasive mammary tumorigenesis, we identified that loss of function of interferon regulatory factor 5 (IRF5) is a predictor of metastasis and survival. Histologic analysis of Irf5-/- mammary glands revealed expansion of luminal and myoepithelial cells, loss of organized glandular structure, and altered terminal end budding and migration. RNA-seq and ChIP-seq analyses of primary mammary epithelial cells from Irf5+/+ and Irf5-/- littermate mice revealed IRF5-mediated transcriptional regulation of proteins involved in ribosomal biogenesis. Using an invasive model of breast cancer lacking Irf5, we demonstrate that IRF5 re-expression inhibits tumor growth and metastasis via increased trafficking of tumor infiltrating lymphocytes and altered tumor cell protein synthesis. These findings uncover a new function for IRF5 in the regulation of mammary tumorigenesis and metastasis.

Breast cancer is the second leading cause of death for women in the United States. However, only 10% of breast cancers have been linked to inherited genomic mutations. Thus, identifying biomarkers to predict cancer progression and metastasis remains a clear need in the research and medical world. Here, we report a novel role for Interferon Regulatory Factor 5 (IRF5) in mammary gland development, tumorigenesis, and metastasis. Historically, IRF5 has been studied as a transcription factor in the context of genetic risk for autoimmune diseases. However, mining of The Cancer Genome Atlas revealed that loss of IRF5 expression in human breast cancer is significantly linked with progression to high grade carcinoma, increased metastasis, and decreased overall and recurrence-free survival. Supporting these analyses, we demonstrated that female Irf5-/- BALB/c mice have higher incidence of spontaneous atypical ductal hyperplasia (ADH), increased progression to DCIS, and ultimately, increased incidence of IDC. Using qPCR, FISH and IHC, we confirmed that IRF5 is expressed in both luminal and basal myoepithelial cells, but expression is higher in basal cells. Histologic analysis of whole mount preparations of Irf5-/- mammary glands revealed aberrant ductal morphogenesis, characterized by expansion of luminal and basal myoepithelial cells with a loss of organized glandular structure. RNAseq of primary mammary epithelial cells from wild type and Irf5-/- littermate mice showed Irf5-/- mammary epithelial cells to be enriched in ribosome biogenesis pathways, the physiologic consequences of which were demonstrated through increased rates of protein synthesis. Transferring our studies in vivo, we demonstrated that loss of tumor IRF5 expression resulted in decreased tumor-infiltrating lymphocytes and increased pulmonary metastasis in the murine orthotopic 4T1 implantation model. Mechanistically, we found that—as in our studies utilizing primary mammary epithelial cells—IRF5 expression in tumors regulated protein translation and ribosome biogenesis. In light of these findings, we propose IRF5 as a novel prognostic biomarker, loss of which alters mammary gland development, drives tumor initiation and metastasis, and dysregulates mammary epithelial cell protein synthesis. Citation Format: Betsy Barnes, Zarina Brune, Matthew Rice, Carter Somerville. Rediscovering IRF5: A prognostic indicator with novel roles in mammary gland development, ribosome biogenesis, tumor initiation, and metastasis [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-15-01.

Metastasis of breast cancer and recurrence to incurable disease are leading causes of mortality. Metastasis is driven by extensive cooperation between a tumor and its microenvironment, resulting in the adaptation of molecular mechanisms that evade the immune system and enable pre-metastatic niche (PMN) formation. Little is known of the tumor-intrinsic factors that regulate these mechanisms. Here we show that expression of the transcription factor interferon regulatory factor 5 (IRF5) in breast cancer clinically correlates with tumor immunogenicity, increased T cell and M1 macrophage recruitment and prolonged survival. Conversely, loss of tumor-intrinsic Irf5 establishes a tumor microenvironment and PMN that supports metastasis. Mechanistically, Irf5 alters the composition and secretion of tumor-derived extracellular vesicles (t-dEVs). Upon whole-body pre-conditioning with t-dEVs from Irf5-positive or −negative breast cancer cells, we found increased lung metastatic colonization that replicated findings from orthotopically implanted breast cancer cells. Collectively, our findings uncover an essential role for IRF5 in breast cancer metastasis through its regulation of t-dEV and immune reprogramming.